Climate of Los Angeles
{{short description|none}}
File:Los Angeles, CA from the air.jpg
The climate of Los Angeles is mild to hot year-round, and mostly dry. It is classified as borderline Mediterranean and semi-arid. The city is characterized by seasonal changes in rainfall—with a dry summer and a winter rainy season. Under the Köppen climate classification, the coastal areas are classified as BSh and Csb, while the inland areas are classified as BSh and Csa.
The Los Angeles area contains microclimates, where daytime temperatures can vary as much as {{convert|36|F-change}} between inland areas such as the San Fernando Valley or San Gabriel Valley, and the coastal Los Angeles Basin. The two northernmost cities in Los Angeles County, Palmdale and Lancaster, rarely (although more often than the other cities in the county) receive snow in the winter due to their altitude of approximately {{convert|2500|ft|m}}, while their summers are hotter than the rest of the county.
Classifications
{{Schemebox
|city =Los Angeles
| source_k ={{Cite web|url=http://www.weatherbase.com/weather/weather-summary.php3?s=159227&cityname=Los+Angeles,+California,+United+States+of+America|title=Los Angeles, California Köppen Climate Classification (Weatherbase)|website=Weatherbase|access-date=2019-07-01|archive-date=2023-09-12|archive-url=https://web.archive.org/web/20230912221118/http://www.weatherbase.com/weather/weather-summary.php3?s=159227&cityname=Los+Angeles,+California,+United+States+of+America|url-status=live}}{{Cite book|url=https://books.google.com/books?id=rEwGBAAAQBAJ&q=los+angeles+koppen+csa&pg=PA11|title=Appendix 2: Köppen Climate Classification: Single appendix from the eBook Understanding Physical Geography|last=Pidwirny|first=Michael|date=2019-06-16|publisher=Our Planet Earth Publishing|language=en|access-date=2020-12-09|archive-date=2023-09-12|archive-url=https://web.archive.org/web/20230912221118/https://books.google.com/books?id=rEwGBAAAQBAJ&q=los+angeles+koppen+csa&pg=PA11|url-status=live}}{{Cite journal|last=Kesseli|first=John E.|date=1942|title=The Climates of California According to the Köppen Classification|journal=Geographical Review|volume=32|issue=3|pages=476–480|doi=10.2307/210390|issn=0016-7428|jstor=210390|bibcode=1942GeoRv..32..476K }}
| initial_k ={{KoppenClimate|Csa|Csa, Csb, BSh}}
| description_k =Hot-summer Mediterranean climate
Warm-summer Mediterranean climate
Hot-semi-arid climate
| source_t ={{Cite web|url=https://kkh.ltrr.arizona.edu/kkh/climate/trewartha_maps.htm|title=Trewartha maps|website=kkh.ltrr.arizona.edu|access-date=2019-07-01|archive-date=2019-01-31|archive-url=https://web.archive.org/web/20190131040836/https://kkh.ltrr.arizona.edu/kkh/climate/trewartha_maps.htm|url-status=live}}{{Citation|last=Peterson|first=Adam|title=English: Trewartha climate types for the contiguous United States|date=2016-09-22|url=https://commons.wikimedia.org/wiki/File:US_trewartha.svg|access-date=2019-07-01|archive-date=2019-03-30|archive-url=https://web.archive.org/web/20190330195901/https://commons.wikimedia.org/wiki/File:US_trewartha.svg|url-status=live}}
| initial_t ={{TrewarthaClimate|Cs}}
| description_t =Subtropical dry summer climate
| initial_a ={{n/a}}
| description_a =Subtropical climate
| initial_s ={{n/a}}
| description_s =Mediterranean climate
| initial_tw ={{center|D B'3}}
| description_tw =Semiarid and warm-mesothermal
| source_n ={{Cite web|url=https://www.spektrum.de/lexikon/geographie/klimaklassifikation/4159|title=Klimaklassifikation|website=www.spektrum.de|language=de|access-date=2019-07-01|archive-date=2019-07-01|archive-url=https://web.archive.org/web/20190701173007/https://www.spektrum.de/lexikon/geographie/klimaklassifikation/4159|url-status=live}}{{Cite web|url=https://www.klett.de/sixcms/media.php/klett72.a.427.de/upload/klimazonen_neef.jpg|title=Klimazonen nach E. Neef (1989)|publisher=Klett-Perthes|access-date=2019-07-01|archive-date=2019-07-01|archive-url=https://web.archive.org/web/20190701173006/https://www.klett.de/sixcms/media.php/klett72.a.427.de/upload/klimazonen_neef.jpg|url-status=live}}
| initial_n ={{n/a}}
| description_n =West side/Winter rainy climate
}}
Temperatures and seasons
The primary weather station for Los Angeles is located near downtown at the south side of Dodger Stadium campus, and this article refers primarily to climate data generated by this station as representative of the Los Angeles metropolitan area as a whole.
The summer dry season normally runs from May through October, when clear skies, hot temperatures, and very little change in sensible weather occur from day to day. Average high temperatures are in the lower 80's F (26-28 C) with overnight lows in the lower 60's F (15-17 C). During this season, there is essentially no rainfall, and both July and August average less than 0.05 of an inch (1.27 mm) of monthly precipitation.
The winter wet season normally runs from November through April. Precipitation episodes in Los Angeles, with a few notable exceptions, are largely caused by extratropical disturbances approaching California from the west or northwest during the winter season. Of the total annual precipitation recorded in Los Angeles, 92% falls between November 1 and April 30.{{Cite web|url=http://www.wrh.noaa.gov/lox/climate/climate_intro.php|title=National Weather Service - NWS Los Angeles/Oxnard|website=www.wrh.noaa.gov|access-date=2018-06-15|archive-date=2012-01-21|archive-url=https://web.archive.org/web/20120121124215/http://www.wrh.noaa.gov/lox/climate/climate_intro.php|url-status=live}} Despite the increased rain, the winter months are still frequently sunny and pleasant, however, with mild-to-warm temperatures. The average highs range from the upper 60's F to lower 70's F (17-21 C) with cooler overnight lows in the upper 40's and lower 50's F (8-12 C).
{{Los Angeles weatherbox}}
{{Weather box
|width =
|collapsed =
|single line = yes
|location = Los Angeles (UCLA, 1991–2020 normals, extremes 1933–present)
|Jan record high F = 91
|Feb record high F = 91
|Mar record high F = 94
|Apr record high F = 103
|May record high F = 97
|Jun record high F = 102
|Jul record high F = 106
|Aug record high F = 99
|Sep record high F = 109
|Oct record high F = 103
|Nov record high F = 99
|Dec record high F = 94
|year record high F = 109
|Jan avg record high F = 82.4
|Feb avg record high F = 81.9
|Mar avg record high F = 83.3
|Apr avg record high F = 86.0
|May avg record high F = 84.1
|Jun avg record high F = 84.0
|Jul avg record high F = 87.9
|Aug avg record high F = 89.8
|Sep avg record high F = 94.9
|Oct avg record high F = 92.6
|Nov avg record high F = 87.8
|Dec avg record high F = 80.3
|year avg record high F = 97.4
|Jan high F = 67.7
|Feb high F = 67.0
|Mar high F = 68.0
|Apr high F = 69.6
|May high F = 70.2
|Jun high F = 72.9
|Jul high F = 76.9
|Aug high F = 78.8
|Sep high F = 78.7
|Oct high F = 76.2
|Nov high F = 72.1
|Dec high F = 67.1
|year high F = 72.1
|Jan mean F = 59.8
|Feb mean F = 59.1
|Mar mean F = 60.0
|Apr mean F = 61.8
|May mean F = 63.2
|Jun mean F = 66.0
|Jul mean F = 69.6
|Aug mean F = 71.0
|Sep mean F = 70.6
|Oct mean F = 67.9
|Nov mean F = 63.7
|Dec mean F = 59.3
|year mean F = 64.3
|Jan low F = 51.9
|Feb low F = 51.1
|Mar low F = 52.1
|Apr low F = 53.6
|May low F = 56.3
|Jun low F = 59.1
|Jul low F = 62.4
|Aug low F = 63.1
|Sep low F = 62.5
|Oct low F = 59.6
|Nov low F = 55.4
|Dec low F = 51.4
|year low F = 56.5
|Jan avg record low F = 42.9
|Feb avg record low F = 43.0
|Mar avg record low F = 44.4
|Apr avg record low F = 46.6
|May avg record low F = 50.8
|Jun avg record low F = 54.2
|Jul avg record low F = 57.7
|Aug avg record low F = 58.3
|Sep avg record low F = 56.6
|Oct avg record low F = 53.0
|Nov avg record low F = 47.3
|Dec avg record low F = 43.4
|year avg record low F = 40.8
|Jan record low F = 30
|Feb record low F = 33
|Mar record low F = 34
|Apr record low F = 37
|May record low F = 43
|Jun record low F = 44
|Jul record low F = 51
|Aug record low F = 50
|Sep record low F = 47
|Oct record low F = 40
|Nov record low F = 33
|Dec record low F = 25
|year record low F = 25
|precipitation colour = green
|Jan precipitation inch = 4.14
|Feb precipitation inch = 4.73
|Mar precipitation inch = 2.73
|Apr precipitation inch = 0.77
|May precipitation inch = 0.42
|Jun precipitation inch = 0.11
|Jul precipitation inch = 0.03
|Aug precipitation inch = 0.01
|Sep precipitation inch = 0.15
|Oct precipitation inch = 0.72
|Nov precipitation inch = 0.99
|Dec precipitation inch = 2.93
|year precipitation inch = 17.73
|snow colour =
|Jan snow inch = 0.0
|Feb snow inch = 0.0
|Mar snow inch = 0.0
|Apr snow inch = 0.0
|May snow inch = 0.0
|Jun snow inch = 0.0
|Jul snow inch = 0.0
|Aug snow inch = 0.0
|Sep snow inch = 0.0
|Oct snow inch = 0.0
|Nov snow inch = 0.0
|Dec snow inch = 0.0
|year snow inch = 0.0
|unit precipitation days = 0.01 in
|Jan precipitation days = 6.3
|Feb precipitation days = 6.5
|Mar precipitation days = 5.1
|Apr precipitation days = 2.5
|May precipitation days = 1.7
|Jun precipitation days = 0.9
|Jul precipitation days = 0.6
|Aug precipitation days = 0.2
|Sep precipitation days = 0.5
|Oct precipitation days = 2.3
|Nov precipitation days = 3.1
|Dec precipitation days = 5.3
|year precipitation days = 35.0
|unit snow days = 0.1 in
|Jan snow days = 0.0
|Feb snow days = 0.0
|Mar snow days = 0.0
|Apr snow days = 0.0
|May snow days = 0.0
|Jun snow days = 0.0
|Jul snow days = 0.0
|Aug snow days = 0.0
|Sep snow days = 0.0
|Oct snow days = 0.0
|Nov snow days = 0.0
|Dec snow days = 0.0
|year snow days = 0.0
|source 1 = NOAA{{cite web
|url = https://www.ncei.noaa.gov/access/services/data/v1?dataset=normals-monthly-1991-2020&stations=USC00049152&format=pdf&dataTypes=MLY-TMAX-NORMAL,MLY-TMIN-NORMAL,MLY-TAVG-NORMAL,MLY-PRCP-NORMAL,MLY-SNOW-NORMAL
|title = NOAA NCEI U.S. Climate Normals Quick Access
|publisher = National Oceanic and Atmospheric Administration
|access-date = July 26, 2023
|archive-date = July 26, 2023
|archive-url = https://web.archive.org/web/20230726133537/https://www.ncei.noaa.gov/access/services/data/v1?dataset=normals-monthly-1991-2020&stations=USC00049152&format=pdf&dataTypes=MLY-TMAX-NORMAL,MLY-TMIN-NORMAL,MLY-TAVG-NORMAL,MLY-PRCP-NORMAL,MLY-SNOW-NORMAL
|url-status = live}}
|source 2 = XMACIS2 (mean maxima/minima 1991–2020){{cite web
|url = https://xmacis.rcc-acis.org/
|publisher = National Oceanic and Atmospheric Administration
|title = xmACIS2
|access-date = July 26, 2023
|archive-date = August 15, 2019
|archive-url = https://web.archive.org/web/20190815183401/http://xmacis.rcc-acis.org/
|url-status = live
}}}}
{{Graph:Weather monthly history
| table=ncei.noaa.gov/weather/Los Angeles.tab
| title=Downtown Los Angeles monthly weather statistics
}}
| class="wikitable"
|+Hottest and coldest, wettest and driest averages for a month (°F/inch and °C/mm), 1895–2019{{Cite web|url=http://prism.oregonstate.edu/explorer/|title=PRISM Climate Group, Oregon State U|website=prism.oregonstate.edu|access-date=March 28, 2019|archive-date=July 25, 2019|archive-url=https://web.archive.org/web/20190725164937/http://prism.oregonstate.edu/explorer/|url-status=live}} !Month !Jan !Feb !Mar !Apr !May !Jun !Jul !Aug !Sep !Oct !Nov !Dec |
| Hottest
|{{convert|63.9|F}} |{{convert|64.2|F}} |{{convert|67.5|F}} |{{convert|68.2|F}} |{{convert|71.5|F}} |{{convert|75.9|F}} |{{convert|79.8|F}} |{{convert|79.0|F}} |{{convert|80.3|F}} |{{convert|75.4|F}} |{{convert|66.9|F}} |{{convert|62.2|F}} |
| Coldest
|{{convert|46.7|F}} |{{convert|51.1|F}} |{{convert|52.0|F}} |{{convert|55.2|F}} |{{convert|57.2|F}} |{{convert|62.9|F}} |{{convert|66.2|F}} |{{convert|66.3|F}} |{{convert|63.1|F}} |{{convert|57.8|F}} |{{convert|55.2|F}} |{{convert|49.4|F}} |
| Wettest
|{{convert|14.43|in}} |{{convert|15.23|in}} |{{convert|10.44|in}} |{{convert|7.31|in}} |{{convert|3.83|in}} |{{convert|0.98|in}} |{{convert|0.43|in}} |{{convert|2.54|in}} |{{convert|5.13|in}} |{{convert|5.13|in}} |{{convert|9.96|in}} |{{convert|11.46|in}} |
| Driest
|{{convert|0|in}} |{{convert|0|in}} |{{convert|0|in}} |{{convert|0|in}} |{{convert|0|in}} |{{convert|0|in}} |{{convert|0|in}} |{{convert|0|in}} |{{convert|0|in}} |{{convert|0|in}} |{{convert|0|in}} |{{convert|0|in}} |
=Summer=
File:MonsoonLA.gif thunderstorms moving westward across Greater Los Angeles, bringing heavy rain, strong winds, and intense lightning.]]
Summers are warm to hot, and nearly completely dry. The summer temperature pattern usually begins in late June or early July, and lasts through September or October, although it may start as early as late May. In August, the average high/low at the University of Southern California downtown campus are {{convert|84.8|F|1|abbr=on}} and {{convert|65.6|F|1|abbr=on}}. The same figures at Los Angeles International Airport, approximately {{convert|12|mi|km}} to the southwest and near the ocean, are {{convert|76.6|F|1|abbr=on}} and {{convert|64.2|F|1|abbr=on}}. However, temperatures across the region often exceed {{convert|90|F|C}} during the summer. This happens when an atmospheric high-pressure area becomes dominant over the Great Basin of Nevada and Utah (a frequent occurrence), and the resulting offshore flow of the atmospheric air mass pauses the normal coastal sea breeze in Los Angeles. July, August and September are the hottest months, with September 27, 2010, holding the all-time record of {{convert|113|F|C}}. Skies are nearly constantly sunny, unless interrupted in late spring and early summer by the June Gloom pattern, which is unpredictable year to year.
While very uncommon on the coastal strip, the North American Monsoon can bring occasional thunderstorms and high humidity to Greater Los Angeles in the summer and early fall.
File:June Gloom at Seal Beach, California, June 2013.jpg, June 2013.]]
=Winter=
Winters are mild to moderately warm, with average high temperatures at the Downtown/USC weather station of {{convert|68|F|C}} and lows of {{convert|48|F|C}}, with occasional heavy rainfall. Downtown/USC station has recorded a record-low high temperature of 43 °F on January 9, 1922. Regardless of this record, the high temperature almost never ever fails to hit 50 °F all winter long. Across the coastal basin, temperatures rarely drop below {{convert|40|F|C}}, although light frost does occasionally form during cooler nights, at least in areas removed from the direct influence of the coastal air (approximately {{convert|5|mi|km|0}} inland from the beach). The last severe cold outbreak in the Los Angeles area occurred in December 1990, when temperatures dropped below freezing across a major portion of the coastal plain and into the low to mid-20s °F over inland valleys. Temperatures stayed below freezing for up to eight hours at some valley locations, resulting in significant damage to plants and commercial agriculture.{{Cite web|url=https://www.wrh.noaa.gov/lox/climate/climate_intro.php|title=National Weather Service - NWS Los Angeles/Oxnard|website=www.wrh.noaa.gov|access-date=2018-06-15|archive-date=2018-06-15|archive-url=https://web.archive.org/web/20180615190649/https://www.wrh.noaa.gov/lox/climate/climate_intro.php|url-status=live}}
In the winter months, high-pressure systems over the deserts often bring Santa Ana winds, resulting in dry, and dusty days. On rare occasion, temperatures can reach into the {{convert|85|to|95|F|C}} range during Santa Ana Winds even in December or January. Sunny skies characteristically dominate the weather pattern in the winter season, mixed in with the occasional rain producing weather system. Christmas on very rare occasion can feel like the Southern Hemisphere with a record high of 85 °F in 1980. Simultaneously, New York City on the East Coast had a record low of −1 °F the same day [https://www.wunderground.com/article/safety/winter/news/2021-12-22-christmas-extremes-warmest-coldest-snowiest Christmas extremes in US]. However, this type of heat does not occur each December, and milder conditions in the mid-60s to low 70s °F are generally expected throughout the Los Angeles region.
=Spring and autumn=
Spring and autumn hardly exist as such in this climate. Summer temperature patterns of {{convert|75|to|90|F|C}} highs and {{convert|60|to|70|F|C|}} lows usually persist until early November. Likewise, the "winter-season" temperature pattern of {{convert|65|to|75|F|C}} highs and {{convert|45|to|60|F|C}} lows may last through April or May, periodically interrupted by hot Santa Ana wind events for up to a week at a time. The rainy season ends by mid-May. June is a transitional month consisting of less volatile temperatures between {{convert|60|and|80|F|C}} and increased cloudy days, as well as the disappearance of the Santa Ana winds.
Rainfall
File:Griffith Observatory entrance lawn with Hollywood sign.jpg and the Hollywood Sign from the Griffith Observatory lawn, one day after a rain.]]
Most rain occurs during the winter and early to mid spring, typical of a Mediterranean climate. However, the amount received is usually lower than in other Mediterranean climates. The first sporadic rainfall of the rainy season usually occurs in October or November, with heavy rain becoming more common late November through early April. Pineapple Express storms may occur from December to March. On average, February is the wettest month. The rains then taper off in April or by May, which usually see only two to three light rain showers. However, the timing and volume of rains in the winter is highly variable. After a significant rain, the region's air is cleared of the usual atmospheric haze as well as man-made smog, giving exceptionally clear views across the expansive metropolis.
File:Rain clouds over South LA.jpg
Most cold fronts and depressions spun off by the polar low, the strong winter seasonal low-pressure area in the Gulf of Alaska, fail to carry significant precipitable moisture as far south as Los Angeles, resulting in the region's relatively low average rainfall amount of {{convert|12|-|15|in|mm}} even in normal years. However, a "normal" year rarely occurs, since rainfall in Los Angeles is subject to the position and strength of the jet stream, and the strength of the Gulf of Alaska low. Some years, a well-developed series of cold fronts moves into the area with relatively short separation between each, bringing intermittently rainy periods to Los Angeles for several weeks at a time. If this pattern persists in a rainy season, significantly above-average precipitation will be received. Other years, especially in the drought years of 2012–2016, a blocking region of atmospheric high pressure over the eastern Pacific Ocean, between Alaska and the Pacific Northwest, diverts the jet stream and its flow of cold fronts far to the north through Canada and down into the U.S. Midwest, leaving the U.S. west coast and especially Los Angeles under warm and dry conditions for weeks to months at a time.
Because the rainy season begins in late fall and ends in early to mid spring, precipitation is measured using the water year instead of the calendar year to give an accurate picture of each rainy season's precipitation amounts. Each water year begins October 1 and ends the following September 30, during the driest part of the year.
Sometimes rainfall can occur in the summer from westward-straying monsoon thunderstorms, but this is unusual. Even less common is rain from remnants of dissipating eastern Pacific hurricanes. Los Angeles averages only {{convert|14.7|in|mm|0}} of precipitation per year, and this is lower at the coast and higher in the mountains and foothill cities.{{cite web | url=https://wrcc.dri.edu/cgi-bin/cliMAIN.pl?ca5115 | title=USC rainfall totals | access-date=9 April 2020 | archive-date=19 September 2020 | archive-url=https://web.archive.org/web/20200919014621/https://wrcc.dri.edu/cgi-bin/cliMAIN.pl?ca5115 | url-status=live }} Snow is extremely rare in the Greater Los Angeles area and basin, but the nearby San Gabriel Mountains and San Bernardino Mountains typically receive a heavy amount of snow every winter season. The greatest snowfall recorded in downtown Los Angeles was {{convert|2|in|cm|0}} on January 15, 1932.{{cite news
|last=Rasmussen
|first=Cecilia
|url=https://www.latimes.com/archives/la-xpm-2005-mar-10-me-surroundings10-story.html
|title=We're Not in Kansas, but We Do Get Twisters – Los Angeles Times
|publisher=Articles.latimes.com
|date=2005-03-10
|access-date=2009-01-08
|archive-date=2009-06-12
|archive-url=https://web.archive.org/web/20090612081703/http://articles.latimes.com/2005/mar/10/local/me-surroundings10
|url-status=live
}}Burt, Christopher. Extreme Weather: A Guide and Record Book. New York: Norton, 2004: 100.
Los Angeles Airport has an estimated pan evaporation rate of {{convert|65.5|in|mm|0}} per year.[https://pacinst.org/water-policy-what-about-all-those-swimming-pools-in-los-angeles/#:~:text=How%20much%20water%20is%20lost,diameter%20Class%20A%20evaporation%20pan. Water Policy: What about All Those Swimming Pools in Los Angeles?] {{Webarchive|url=https://web.archive.org/web/20200727133445/https://pacinst.org/water-policy-what-about-all-those-swimming-pools-in-los-angeles/#:~:text=How%20much%20water%20is%20lost,diameter%20Class%20A%20evaporation%20pan. |date=2020-07-27 }} By Peter Gleick, Pacific Institute, December 3, 2013
=El Niño–Southern Oscillation=
Historically, the warm phase of an El Niño–Southern Oscillation (ENSO) regime typically coincides with above-average precipitation across Southern California.{{cite web |url=http://www.water.ca.gov/waterconditions/docs/California_Signficant_Droughts_2015_small.pdf#page=28 |title=ENSO and California Precipitation |publisher=California Department of Water Resources |access-date=29 April 2016 |archive-date=11 November 2016 |archive-url=https://web.archive.org/web/20161111012623/http://www.water.ca.gov/waterconditions/docs/California_Signficant_Droughts_2015_small.pdf#page=28 |url-status=live }} The above-average sea-surface temperatures in the equatorial Pacific Ocean are largely responsible for this as the ocean acts as a rich moisture source for tropical moisture to advect towards the North American continent in atmospheric river events. Prior to the strong El Niño of 2015–2016, the previous two strong El Niño events{{cite web |url=http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ensoyears.shtml |title=Monitoring & Data: ENSO Impacts on the U.S. – Previous Events |publisher=Climate Prediction Center |access-date=2016-04-29 |archive-date=2014-11-29 |archive-url=https://web.archive.org/web/20141129084421/http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ensoyears.shtml |url-status=live }} in 1982–83 and 1997–98 coincided with well above average precipitation across Southern California.{{cite news|url=https://www.latimes.com/local/weather/la-me-ln-where-is-el-nino-20160126-story.html|title=Is El Niño wimping out in Southern California? Not quite|first=Rong-Gong|last=Lin II|newspaper=Los Angeles Times|access-date=2020-04-16|archive-date=2020-04-17|archive-url=https://web.archive.org/web/20200417142813/https://www.latimes.com/local/weather/la-me-ln-where-is-el-nino-20160126-story.html|url-status=live}} While some measurements suggest the 2015-2016 El Niño was the strongest on record since 1950, Southern California received below average precipitation contrary to what the Climate Prediction Center predicted leading up to the winter months.{{cite web |url=http://www.cpc.ncep.noaa.gov/products/archives/long_lead/gifs/2015/201511month.gif |title=Dec–Jan–Feb_2015 |publisher=National Oceanic and Atmospheric Administration – Climate Prediction Center |access-date=29 April 2016 |archive-date=1 June 2016 |archive-url=https://web.archive.org/web/20160601153320/http://www.cpc.ncep.noaa.gov/products/archives/long_lead/gifs/2015/201511month.gif |url-status=live }}
{{wide image|North American Monsoon 20080808 (wide).jpg|1000px|Cumulonimbus thunderheads from the North American Monsoon over the Low Desert, approximately {{convert|100|mi|km}} southeast of Los Angeles, as seen from El Cajon, California.}}
Surrounding areas in the region
=Coastal basin=
The Los Angeles Basin, composed of the coastal plain surrounded by mountains, is generally the coolest in summer and mildest in winter. Overall, it receives less rainfall than the surrounding valleys and mountains.
==Los Angeles International Airport==
Los Angeles International Airport airport and its surroundings (Westchester and El Segundo, as well as Santa Monica, Venice, and the immediately surrounding neighborhoods) are generally the coolest part of the region in the summer, as they receive a near-constant sea breeze. Santa Monica and its environs may be {{convert|10|to|15|F-change|0}} cooler than areas only {{convert|5|mi|km}} further inland. Under the Köppen climate classification, the airport has a semi-arid climate due to its modest winter rainfall and mild mean temperatures. For monthly statistics, see Climate of Los Angeles#Temperatures and seasons
==Santa Monica==
Santa Monica has mean temperatures low enough for its precipitation numbers to still retain a warm-summer Mediterranean climate (Csb).
{{Weather box
|location = Santa Monica Pier, California (on the beach)
|single line = Y
|Jan high F = 63.7
|Feb high F = 63.4
|Mar high F = 62.1
|Apr high F = 63.4
|May high F = 63.6
|Jun high F = 65.9
|Jul high F = 68.8
|Aug high F = 70.3
|Sep high F = 70.5
|Oct high F = 69.6
|Nov high F = 67.3
|Dec high F = 64.8
|year high F = 66.1
|Jan low F = 50.2
|Feb low F = 51.3
|Mar low F = 52.1
|Apr low F = 53.9
|May low F = 56.5
|Jun low F = 59.4
|Jul low F = 62.1
|Aug low F = 63.1
|Sep low F = 62.6
|Oct low F = 59.4
|Nov low F = 54.3
|Dec low F = 50.5
|year low F = 56.3
|rain colour = green
|Jan rain inch = 3.06
|Feb rain inch = 3.29
|Mar rain inch = 2.56
|Apr rain inch = 0.53
|May rain inch = 0.25
|Jun rain inch = 0.04
|Jul rain inch = 0.01
|Aug rain inch = 0.13
|Sep rain inch = 0.17
|Oct rain inch = 0.36
|Nov rain inch = 1.02
|Dec rain inch = 1.85
|Jan rain days = 6.0
|Feb rain days = 5.9
|Mar rain days = 5.1
|Apr rain days = 2.4
|May rain days = 1.0
|Jun rain days = 0.4
|Jul rain days = 0.2
|Aug rain days = 0.5
|Sep rain days = 1.0
|Oct rain days = 1.8
|Nov rain days = 2.5
|Dec rain days = 4.0
{{cite web
| url = http://cdo.ncdc.noaa.gov/climatenormals/clim20/ca/047953.pdf
| title = NCDC: U.S. Climate Normals
| publisher = National Oceanic and Atmospheric Administration
| access-date = 2010-09-05
| archive-url = https://web.archive.org/web/20140713204940/http://cdo.ncdc.noaa.gov/climatenormals/clim20/ca/047953.pdf
| archive-date = 2014-07-13
| url-status = dead
}}
|date=August 2010
}}
==Culver City, Inglewood and Palms area==
Culver City, Inglewood, Palms, and surrounding areas are only a few miles inland from Santa Monica and the beach, but reach temperatures up to 10 degrees (F) warmer on average in the summer. Culver City has a semi-arid climate that is still significantly moderated by the Pacific trade winds keeping averages mild compared to areas farther inland.
{{Weather box
|location = Culver City, California
|single line = Y
|Jan high F = 67.3
|Feb high F = 68.6
|Mar high F = 69.3
|Apr high F = 72.6
|May high F = 73.5
|Jun high F = 77.1
|Jul high F = 80.0
|Aug high F = 81.1
|Sep high F = 80.2
|Oct high F = 77.0
|Nov high F = 71.6
|Dec high F = 67.7
|year high F = 73.8
|Jan mean F = 56.7
|Feb mean F = 57.9
|Mar mean F = 59.2
|Apr mean F = 62.3
|May mean F = 64.6
|Jun mean F = 68.0
|Jul mean F = 70.8
|Aug mean F = 71.7
|Sep mean F = 70.8
|Oct mean F = 67.1
|Nov mean F = 61.2
|Dec mean F = 57.0
|year mean F = 63.9
|Jan low F = 46.1
|Feb low F = 47.2
|Mar low F = 49.1
|Apr low F = 52.0
|May low F = 55.7
|Jun low F = 58.8
|Jul low F = 61.5
|Aug low F = 62.2
|Sep low F = 61.3
|Oct low F = 57.2
|Nov low F = 50.8
|Dec low F = 46.3
|year low F = 54.0
|rain colour = green
|Jan rain inch = 3.19
|Feb rain inch = 3.25
|Mar rain inch = 2.66
|Apr rain inch = 0.58
|May rain inch = 0.26
|Jun rain inch = 0.04
|Jul rain inch = 0.02
|Aug rain inch = 0.07
|Sep rain inch = 0.08
|Oct rain inch = 0.33
|Nov rain inch = 0.94
|Dec rain inch = 1.90
|year rain inch = 13.32
|Jan rain days = 5.7
|Feb rain days = 5.3
|Mar rain days = 5.8
|Apr rain days = 1.7
|May rain days = 0.7
|Jun rain days = 0.2
|Jul rain days = 0.3
|Aug rain days = 0.2
|Sep rain days = 0.6
|Oct rain days = 1.1
|Nov rain days = 1.9
|Dec rain days = 4.0
|year rain days = 27.5
|unit rain days = 0.01 inch
{{cite web
| url = http://cdo.ncdc.noaa.gov/climatenormals/clim20/ca/042214.pdf
| title = Climatography of the United States No. 20 (1971–2000) – Culver City, CA
| publisher = National Oceanic and Atmospheric Administration
| year = 2004
| access-date = 2010-07-25
| archive-url = https://web.archive.org/web/20140815135746/http://cdo.ncdc.noaa.gov/climatenormals/clim20/ca/042214.pdf
| archive-date = 2014-08-15
| url-status = dead
}}
|date=August 2010}}
==Long Beach==
Long Beach, located in the coastal basin about {{convert|20|mi|km|-1}} to the south of downtown Los Angeles, has a coastally-influenced climate, but is not as cool as Santa Monica, or the Westside, or the South Bay during the summer. Long Beach sits on a south-facing section of coast, and does not receive as much sea breeze cooling from the prevailing westerly/south-westerly winds (as these winds may pass over the Palos Verdes Peninsula, San Pedro, and the twin ports first). Long Beach's high temperature can compete with those of downtown Los Angeles. Locations further north in Long Beach, which stretches over {{convert|8.5|mi|km}} northward from the water, can be considerably warmer than Long Beach's coast and airport weather station.
{{Weather box
|location = Long Beach, California (Long Beach Airport)
|single line = Y
|Jan record high F = 93
|Feb record high F = 91
|Mar record high F = 98
|Apr record high F = 105
|May record high F = 104
|Jun record high F = 109
|Jul record high F = 107
|Aug record high F = 105
|Sep record high F = 111
|Oct record high F = 111
|Nov record high F = 101
|Dec record high F = 92
|year record high F = 111
|Jan high F = 67.4
|Feb high F = 67.2
|Mar high F = 68.6
|Apr high F = 71.7
|May high F = 73.6
|Jun high F = 76.7
|Jul high F = 81.9
|Aug high F = 83.8
|Sep high F = 82.1
|Oct high F = 77.2
|Nov high F = 72.1
|Dec high F = 66.8
|year high F = 74.1
|Jan mean F = 56.7
|Feb mean F = 57.6
|Mar mean F = 59.6
|Apr mean F = 62.4
|May mean F = 65.6
|Jun mean F = 68.9
|Jul mean F = 73.2
|Aug mean F = 74.3
|Sep mean F = 72.7
|Oct mean F = 67.7
|Nov mean F = 61.4
|Dec mean F = 56.3
|year mean F = 64.7
|Jan low F = 46.1
|Feb low F = 48.0
|Mar low F = 50.5
|Apr low F = 53.2
|May low F = 57.6
|Jun low F = 61.0
|Jul low F = 64.5
|Aug low F = 64.9
|Sep low F = 63.2
|Oct low F = 58.3
|Nov low F = 50.8
|Dec low F = 45.8
|year low F = 55.3
|Jan record low F = 25
|Feb record low F = 33
|Mar record low F = 33
|Apr record low F = 38
|May record low F = 40
|Jun record low F = 47
|Jul record low F = 51
|Aug record low F = 51
|Sep record low F = 50
|Oct record low F = 39
|Nov record low F = 34
|Dec record low F = 28
|year record low F = 25
|rain colour = green
|Jan rain inch = 2.60
|Feb rain inch = 3.09
|Mar rain inch = 1.87
|Apr rain inch = 0.60
|May rain inch = 0.21
|Jun rain inch = 0.07
|Jul rain inch = 0.03
|Aug rain inch = 0.03
|Sep rain inch = 0.18
|Oct rain inch = 0.63
|Nov rain inch = 1.00
|Dec rain inch = 1.95
|year rain inch = 12.26
|unit rain days = 0.01 in
|Jan rain days = 5.9
|Feb rain days = 6.5
|Mar rain days = 5.3
|Apr rain days = 3.1
|May rain days = 1.1
|Jun rain days = 0.7
|Jul rain days = 0.5
|Aug rain days = 0.3
|Sep rain days = 0.9
|Oct rain days = 2.5
|Nov rain days = 3.4
|Dec rain days = 5.0
|source 1 = NOAA{{cite web
| url = http://www.nws.noaa.gov/climate/xmacis.php?wfo=lox
| title = NOWData – NOAA Online Weather Data
| publisher = National Oceanic and Atmospheric Administration
| access-date = July 3, 2013
| archive-date = November 21, 2014
| archive-url = https://web.archive.org/web/20141121190103/http://www.nws.noaa.gov/climate/xmacis.php?wfo=lox
| url-status = live
}}
|date=August 2010
}}
=San Fernando Valley=
The San Fernando Valley is known for significantly higher temperatures than the coastal basin. Canoga Park and Woodland Hills, in the south-west end of the valley, typically record the highest temperatures. The all-time high of {{convert|121|F|C}}{{Cite web|url = https://abcnews.go.com/US/los-angeles-records-citys-highest-temperature-record/story?id=72855640#:~:text=Temperatures%20in%20one%20part%20of,with%20a%20dangerous%20heat%20wave.|title = Los Angeles County records its highest temperature on record|website = ABC News|access-date = 2021-01-26|archive-date = 2021-01-26|archive-url = https://web.archive.org/web/20210126020945/https://abcnews.go.com/US/los-angeles-records-citys-highest-temperature-record/story?id=72855640#:~:text=Temperatures%20in%20one%20part%20of,with%20a%20dangerous%20heat%20wave.|url-status = live}} nearly rivals the record high temperatures of Phoenix, Arizona ({{convert|122|F|C}}) and Palm Springs ({{convert|123|F|C}}). The city of Burbank, at the eastern end of the Valley, is also known for being significantly hotter than downtown Los Angeles, which is only {{convert|9|mi|km}} to the south. During winter both the Canoga Park and Burbank weather stations are significantly wetter than some coastal stations and thus retain hot-summer Mediterranean climates (Csa). By comparison, Canoga Park has quite cool summer nights, in contrast to many other interior Southern California areas.
{{Weather box
|collapsed =
|location = Los Angeles (Canoga Park, in the San Fernando Valley)
|single line = Y
|Jan record high F=93
|Feb record high F=94
|Mar record high F=101
|Apr record high F=105
|May record high F=113
|Jun record high F=113
|Jul record high F=115
|Aug record high F=116
|Sep record high F=115
|Oct record high F=110
|Nov record high F=101
|Dec record high F=96
|year record high F=116
|Jan high F = 67.9
|Feb high F = 69.9
|Mar high F = 72.0
|Apr high F = 77.7
|May high F = 81.3
|Jun high F = 88.8
|Jul high F = 95.0
|Aug high F = 96.0
|Sep high F = 91.7
|Oct high F = 84.4
|Nov high F = 74.7
|Dec high F = 68.8
|year high F = 80.7
|Jan mean F = 53.7
|Feb mean F = 55.4
|Mar mean F = 57.2
|Apr mean F = 61.3
|May mean F = 65.2
|Jun mean F = 71.0
|Jul mean F = 76.0
|Aug mean F = 76.8
|Sep mean F = 73.5
|Oct mean F = 66.8
|Nov mean F = 58.2
|Dec mean F = 53.6
|year mean F = 64.1
|Jan low F = 39.5
|Feb low F = 40.9
|Mar low F = 42.3
|Apr low F = 44.8
|May low F = 49.1
|Jun low F = 53.2
|Jul low F = 56.9
|Aug low F = 57.6
|Sep low F = 55.2
|Oct low F = 49.2
|Nov low F = 41.7
|Dec low F = 38.3
|year low F = 47.4
|Jan record low F=19
|Feb record low F=18
|Mar record low F=26
|Apr record low F=30
|May record low F=33
|Jun record low F=36
|Jul record low F=42
|Aug record low F=42
|Sep record low F=38
|Oct record low F=27
|Nov record low F=23
|Dec record low F=20
|year record low F=18
|rain colour = green
|Jan rain inch = 3.83
|Feb rain inch = 4.40
|Mar rain inch = 3.60
|Apr rain inch = 0.88
|May rain inch = 0.32
|Jun rain inch = 0.07
|Jul rain inch = 0.01
|Aug rain inch = 0.15
|Sep rain inch = 0.24
|Oct rain inch = 0.62
|Nov rain inch = 1.29
|Dec rain inch = 2.38
|Jan rain days = 6.2
|Feb rain days = 5.9
|Mar rain days = 6.1
|Apr rain days = 3.0
|May rain days = 1.3
|Jun rain days = 0.4
|Jul rain days = 0.1
|Aug rain days = 0.7
|Sep rain days = 1.3
|Oct rain days = 2.0
|Nov rain days = 3.2
|Dec rain days = 4.4
{{cite web
| url = http://cdo.ncdc.noaa.gov/climatenormals/clim20/ca/041484.pdf
| title = Climatography of the United States No. 20 (1971–2000) – Canoga Park Pierce Collg, CA
| year = 2004
| publisher = National Oceanic and Atmospheric Administration
| access-date = 2010-06-19
| archive-url = https://web.archive.org/web/20130902181245/http://cdo.ncdc.noaa.gov/climatenormals/clim20/ca/041484.pdf
| archive-date = 2013-09-02
| url-status = dead
}}
|date=August 2010
}}
{{Weather box|location = Burbank, California
|single line = Y
|Jan record high F = 93
|Feb record high F = 92
|Mar record high F = 98
|Apr record high F = 105
|May record high F = 107
|Jun record high F = 111
|Jul record high F = 114
|Aug record high F = 111
|Sep record high F = 114
|Oct record high F = 108
|Nov record high F = 102
|Dec record high F = 95
|year record high F =
|Jan high F = 70
|Feb high F = 71
|Mar high F = 74
|Apr high F = 77
|May high F = 82
|Jun high F = 85
|Jul high F = 90
|Aug high F = 92
|Sep high F = 91
|Oct high F = 83
|Nov high F = 76
|Dec high F = 70
|year high F =
|Jan low F = 45
|Feb low F = 46
|Mar low F = 47
|Apr low F = 50
|May low F = 55
|Jun low F = 61
|Jul low F = 64
|Aug low F = 65
|Sep low F = 63
|Oct low F = 57
|Nov low F = 48
|Dec low F = 45
|year low F =
|Jan record low F = 22
|Feb record low F = 27
|Mar record low F = 22
|Apr record low F = 32
|May record low F = 39
|Jun record low F = 43
|Jul record low F = 45
|Aug record low F = 46
|Sep record low F = 43
|Oct record low F = 33
|Nov record low F = 29
|Dec record low F = 22
|year record low F =22
|rain colour = green
|Jan rain inch = 3.53
|Feb rain inch = 4.62
|Mar rain inch = 2.97
|Apr rain inch = 1.11
|May rain inch = .35
|Jun rain inch = .11
|Jul rain inch = .02
|Aug rain inch = .07
|Sep rain inch = .23
|Oct rain inch = .97
|Nov rain inch = 1.07
|Dec rain inch = 2.40
|source 1 = Weather.com{{cite web |url=http://www.weather.com/outlook/health/achesandpains/climatology/monthly/USCA0139 |title=Average weather for Burbank |access-date=March 29, 2008 |publisher=Weather.com |archive-date=October 22, 2012 |archive-url=https://web.archive.org/web/20121022011737/http://www.weather.com/outlook/health/achesandpains/climatology/monthly/USCA0139 |url-status=live }}
|date=August 2010
}}
=Orange County=
==North/Central Orange County==
The climate of Santa Ana, the county seat of Orange County, as well as Anaheim, both in north-central Orange County, are quite similar, and typical of locations on the coastal plain {{convert|10|to|15|mi|km}} inland from the beach. Whilst Santa Ana sits firmly on the border between the semi-arid and the hot-summer Mediterranean climate, Anaheim is firmly a semi-arid climate with very low precipitation for the Los Angeles metropolitan area.
{{Weather box
|location = Santa Ana, California
|single line = Y
|Jan high F = 69
|Feb high F = 70
|Mar high F = 71
|Apr high F = 74
|May high F = 75
|Jun high F = 79
|Jul high F = 83
|Aug high F = 84
|Sep high F = 83
|Oct high F = 80
|Nov high F = 74
|Dec high F = 70
|year high F =
|Jan low F = 47
|Feb low F = 48
|Mar low F = 50
|Apr low F = 52
|May low F = 56
|Jun low F = 60
|Jul low F = 63
|Aug low F = 64
|Sep low F = 63
|Oct low F = 58
|Nov low F = 51
|Dec low F = 46
|year low F =
|rain colour = green
|Jan rain inch = 3.19
|Feb rain inch = 3.03
|Mar rain inch = 2.8
|Apr rain inch = 0.67
|May rain inch = 0.24
|Jun rain inch = 0.12
|Jul rain inch = 0.04
|Aug rain inch = 0.12
|Sep rain inch = 0.35
|Oct rain inch = 0.35
|Nov rain inch = 1.18
|Dec rain inch = 1.77
|date=August 2010}}
{{Weather box
|location = Anaheim, California
|single line = yes
|Jan high F = 69
|Feb high F = 69
|Mar high F = 70
|Apr high F = 73
|May high F = 75
|Jun high F = 79
|Jul high F = 84
|Aug high F = 86
|Sep high F = 85
|Oct high F = 80
|Nov high F = 74
|Dec high F = 70
|year high F = 76
|Jan low F = 45
|Feb low F = 47
|Mar low F = 48
|Apr low F = 51
|May low F = 56
|Jun low F = 60
|Jul low F = 65
|Aug low F = 65
|Sep low F = 63
|Oct low F = 56
|Nov low F = 51
|Dec low F = 44
|year low F =
|rain colour = green
|Jan rain inch = 2.4
|Feb rain inch = 2.8
|Mar rain inch = 2.5
|Apr rain inch = 0.6
|May rain inch = 0.1
|Jun rain inch = 0.1
|Jul rain inch = 0.0
|Aug rain inch = 0.0
|Sep rain inch = 0.1
|Oct rain inch = 0.2
|Nov rain inch = 0.8
|Dec rain inch = 1.3
|date=August 2010}}
Extreme weather
=Records=
In downtown Los Angeles, weather records began on July 1, 1877. The highest temperature recorded in downtown Los Angeles was {{convert|113|F|C}} on September 27, 2010. The lowest temperature was {{convert|28|F|C}} on January 7, 1913, and on January 4, 1949.{{cite web |url=http://climexp.knmi.nl/data/mgdcnUSC00045115.dat |title=Geert Jan van Oldenborgh @ KNMI |website=climexp.knmi.nl |access-date=6 June 2022 |archive-url=https://archive.today/20120712100845/http://climexp.knmi.nl/data/mgdcnUSC00045115.dat |archive-date=12 July 2012 |url-status=dead}} The wettest “rain year” from July to the following June was 1883/1884 with {{convert|38.18|in|mm|1}}, and the driest 2006/2007 with {{convert|3.21|in|mm|1}}.{{Cite web|url=http://www.haldermanhome.com/weather/LARAIN.pdf|title=Los Angeles and San Diego rainfall|access-date=2015-04-18|archive-date=2017-12-07|archive-url=https://web.archive.org/web/20171207192207/http://www.haldermanhome.com/weather/LARAIN.pdf|url-status=live}} The greatest rainfall in one month was {{convert|15.80|in|mm|1}} in December 1889, which also had the most days – twenty – receiving at least {{convert|0.01|in|mm|1}} of rain. The greatest rainfall in 24 hours was {{convert|5.68|in|mm|1}} on March 2, 1938.{{cite web|url=http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?ca5115|title=LOS ANGELES DWTN USC CAMPUS, CALIFORNIA – Climate Summary|publisher=Western Regional Climate Center|access-date=2010-02-06|archive-date=2008-11-02|archive-url=https://web.archive.org/web/20081102202814/http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?ca5115|url-status=live}}
At Los Angeles International Airport, the highest recorded temperature was {{convert|110|F|C}} on September 26, 1963. The lowest temperature was {{convert|27|F|C}} on January 4, 1949. The wettest year was 1983 with {{convert|29.46|in|mm|0}} and the driest year was 1947 with {{convert|2.95|in|mm|1}}. The greatest rainfall in one month was {{convert|13.79|in|mm|0}} in February 1998. The greatest rainfall in 24 hours was {{convert|5.60|in|mm|1}} on November 21, 1967.{{cite web|url=http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?ca5114|title=LOS ANGELES INTL AP, CALIFORNIA – Climate Summary|publisher=Western Regional Climate Center|access-date=2010-02-06|archive-date=2008-06-07|archive-url=https://web.archive.org/web/20080607041553/http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?ca5114|url-status=live}}
In Long Beach, the highest recorded temperature was {{convert|111|F|C}} on October 16, 1958, and October 15, 1961, and again on September 27, 2010. The lowest temperature was {{convert|21|F|C}} on January 20, 1922. The wettest year was 1978 with {{convert|27.67|in|mm|0}}. The driest year was 2002 with {{convert|2.63|in|mm|1}}. The greatest rainfall in one month was {{convert|14.50|in|mm|0}} in January 1969, including a record 24-hour rainfall of {{convert|6.71|in|mm|1}} on January 20 that month.{{cite web |url=http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?ca5082 |title=LONG BEACH, CALIFORNIA (045082): Period of Record Monthly Climate Summary |publisher=Western Regional Climate Center |access-date=2010-02-06 |archive-date=2008-06-07 |archive-url=https://web.archive.org/web/20080607041534/http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?ca5082 |url-status=live }}{{cite web|url=http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?ca5085|title=LONG BEACH DAUGHERTY FLD, CALIFORNIA (045085): Period of Record Monthly Climate Summary|publisher=Western Regional Climate Center|access-date=2010-02-06|archive-date=2008-06-07|archive-url=https://web.archive.org/web/20080607041539/http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?ca5085|url-status=live}}
In San Fernando Valley, the highest recorded temperature was {{convert|121|F|C}} on September 5, 2020. The lowest temperature was {{convert|18|F|C}} on February 6, 1989.{{Cite web|url=http://cdo.ncdc.noaa.gov/climatenormals/clim20/ca/041484.pdf|title=Archived copy|date=September 2, 2013|archive-url=https://web.archive.org/web/20130902181245/http://cdo.ncdc.noaa.gov/climatenormals/clim20/ca/041484.pdf|archive-date=2013-09-02}}
Snowfall inside the city of Los Angeles is rare. The record snowfall occurred on January 19, 1949, when {{convert|3.0|in|cm|1}} of snow fell inside city limits, however Burbank reported 4.7 inches. Since official records were first kept in 1877, the downtown Los Angeles weather station observed measurable snowfall three times, in 1882, 1932, and 1949.{{Cite web|url=https://www.kcet.org/shows/lost-la/why-hasnt-it-snowed-in-los-angeles-since-1962|title=Why Doesn't It Snow in L.A. Anymore?|first=Nathan|last=Masters|date=December 9, 2016|website=KCET|access-date=June 15, 2018|archive-date=June 15, 2018|archive-url=https://web.archive.org/web/20180615140407/https://www.kcet.org/shows/lost-la/why-hasnt-it-snowed-in-los-angeles-since-1962|url-status=live}}
=Santa Ana winds=
{{Main|Santa Ana winds}}
Image:Santa Ana winds - satellite image.jpg in Southern California sweep from the deserts and across the Los Angeles metropolitan area pushing smoke from wildfires far out into the Pacific Ocean.]]
The Santa Ana winds are strong, extremely dry offshore winds that characteristically sweep across Southern California and northern Baja California during late September into early May. They range from hot to cold, depending on the prevailing temperatures in the source region, the Great Basin and upper Mojave Desert. These winds are notorious for causing hot, dry weather due to compressional heating of the lower atmosphere.
Notable Santa Ana windstorms happen several times a year between fall and spring. Once every several years a strong windstorm causes significant damage, toppling or uprooting large old trees and damaging structures across the region.
=Heavy rains, landslides, and debris flows=
While overall precipitation is low, the rain that does fall occasionally comes in brief heavy storms. Combined with steep mountain slopes and recent burn areas from wildfires, these heavy rains often cause landslides and debris flows in foothill areas, damaging structures and blocking roads.
=Thunderstorms, lightning, and tornadoes=
Textbook cumulonimbus-formed summer thunderstorms are fairly rare{{cite web|url=https://www.foxnews.com/us/rare-southern-california-summer-storm-breaks-regional-rainfall-records|title=Rare Southern California summer storm breaks regional rainfall records|date=19 July 2015|publisher=Associated Press|website=Fox News|access-date=2 September 2016|archive-date=14 September 2016|archive-url=https://web.archive.org/web/20160914044830/http://www.foxnews.com/us/2015/07/19/rare-southern-california-summer-storm-breaks-regional-rainfall-records.html|url-status=live}} in Los Angeles, because the atmosphere over the coastal basin is generally too stable and dry, especially during summer, to allow the strong vertical development necessary for mature cumulonimbus clouds. Full, mature thunderstorms can develop in the surrounding deserts and mountains during the summer North American Monsoon, but rarely over the Los Angeles metropolitan region and coastal basin, where the moisture is coming off of the Gulf of Mexico and the Gulf of California. This atmospheric stability is largely due to the cool and persistent marine layer, which is fueled by the constant influx of cold Pacific water via the California Current. Summer thunderstorms that do manage to form on the coastal basin are typically associated with the North American Monsoon and/or tropical cyclones, or downburst winds followed by weak tornadoes, which can bring enough tropical heat and moisture to overcome the cool marine layer, destabilizing the atmosphere.
Though still relatively rare, thunderstorms most often occur during warm southerly-flow winter rain storms. These warm storms are different from the typical northwesterly cold fronts that bring most of the region's winter precipitation. Atmospheric instability caused by these warm winter storm systems allows the formation of small, weak, isolated thunderstorms, which tend to move across the area quickly, producing a few rumbles of thunder, and soon dissipate back into the larger rain storm system. Occasionally, these bring impressive displays of lightning, hail, and damaging winds to small localities within the region. Small, weak, isolated tornadoes can occur during these events, but are exceedingly rare. Likewise, weak-to-moderate-strength waterspouts may form over the ocean (typically off the stretch of coast between Long Beach and Huntington Beach) during warm winter storms, but again, this is very rare.
Sea temperatures
The average annual temperature of the sea is {{convert|63|°F|°C|abbr=on}}, from {{convert|58|°F|°C|abbr=on}} in January to {{convert|68|°F|°C|abbr=on}} in August.[http://www.beachcalifornia.com/beach/california-ocean-temperature.html "Pacific Ocean Temperatures on California Coast"] {{Webarchive|url=https://web.archive.org/web/20111012162654/http://www.beachcalifornia.com/beach/california-ocean-temperature.html |date=2011-10-12 }} – beachcalifornia.com
| class="wikitable" |
| Jan
!Feb !Mar !Apr !May !Jun !Jul !Aug !Sep !Oct !Nov !Dec !Year |
|---|
| style="background: #CCFF99; color: black;"|{{convert|58|°F|°C|abbr=on}}
|style="background: #CCFF99; color: black;"|{{convert|58|°F|°C|abbr=on}} |style="background: #FFFF99; color: black;"|{{convert|60|°F|°C|abbr=on}} |style="background: #FFFF99; color: black;"|{{convert|60|°F|°C|abbr=on}} |style="background: #FFFF99; color: black;"|{{convert|61|°F|°C|abbr=on}} |style="background: #FFFF66; color: black;"|{{convert|63|°F|°C|abbr=on}} |style="background: #FFCC66; color: black;"|{{convert|66|°F|°C|abbr=on}} |style="background: #FFCC66; color: black;"|{{convert|68|°F|°C|abbr=on}} |style="background: #FFCC66; color: black;"|{{convert|67|°F|°C|abbr=on}} |style="background: #FFCC66; color: black;"|{{convert|66|°F|°C|abbr=on}} |style="background: #FFFF66; color: black;"|{{convert|64|°F|°C|abbr=on}} |style="background: #FFFF99; color: black;"|{{convert|60|°F|°C|abbr=on}} |style="background: #FFFF66; color: black;"|{{convert|63|°F|°C|abbr=on}} |
Ultraviolet index
| class="wikitable" style="margin: 1em auto;"
|+Ultraviolet index[https://www.weather-us.com/en/california-usa/los-angeles-climate#uv_index Average UV index Los Angeles, USA] {{Webarchive|url=https://web.archive.org/web/20201031235537/https://www.weather-us.com/en/california-usa/los-angeles-climate#uv_index |date=2020-10-31 }} – weather-atlas.com |
| Jan
!Feb !Mar !Apr !May !Jun !Jul !Aug !Sep !Oct !Nov !Dec !Year |
|---|
| style="background:#f7e400;color:#000000;"|3
|style="background:#f7e400;color:#000000;"|4 |style="background:#f85900;color:#000000;"|6 |style="background:#d8001d;color:#000000;"|8 |style="background:#d8001d;color:#000000;"|9 |style="background:#d8001d;color:#000000;"|10 |style="background:#6b49c8;color:#000000;"|11 |style="background:#d8001d;color:#000000;"| 10 |style="background:#d8001d;color:#000000;"| 8 |style="background:#f85900;color:#000000;"|6 |style="background:#f7e400;color:#000000;"|4 |style="background:#f7e400;color:#000000;"|3 |style="background:#f85900;color:#000000;border-left-width:medium"|6.8 |
Notes
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References
{{Reflist}}
{{ClimateUS
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{{Portal|Los Angeles}}
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Category:Environment of Greater Los Angeles
Category:Los Angeles metropolitan area