Climate in Los Angeles / Forecast

This page is about the changing climate of Los Angeles.

1. LA’s Past and Present Climate

1.1 What is LA’s climate changing from?

1.2 What is LA’s climate changing to?

1.3 LA’s current climate will soon be departed.

2. Climate Forecast for LA

2.1 How hot will it get in LA?

2.2 This is how LA’s climate is changing.

2.3 This is why LA is warming differently in three different locations.

1. LA’s Past and Present Climate

Climate is the usual weather over a long period of time. Climate is different depending where you are on the globe. For tens of thousands to millions of years, Earth has had roughly 16 classes of climate, the same climates we’ve had until the 2000s and 2010s. These climates are changing noticeably now. Some are changing faster than others. What kind of climate do we have now, that is changing? What kind of climate is LA changing to?

1.1 What is LA’s climate changing from?

This shows the two attributes that best describes LA's Mediterranean climate. Graphic.

LA is the crowded, lively city it is largely because it has one of the most comfortable climates in the world. “Hot Summer Mediterranean” is LA’s official climate designation. This dry subtropical climate features warm, dry Summers and mild, rainy winters. The geography of the City of LA sprawls into the “Cool/Warm Mediterranean” climate of the LA foothills and the “Semi-Arid” climate of the Baldwin Hills and the Port of Los Angeles on the coast.

Over the length of the city’s history, long before the era of modern humans, the region that is now Los Angeles has had the same pleasant Mediterranean climate – with possible slight cooling during ice ages – for at least 500 centuries. For the past 50,000 years, the highest temp on a typical Summer day in the Los Angeles Basin has ranged between the mid 70˚s to mid 80˚s, with the temp rarely pushing past 90.˚

en.wikipedia.org/wiki/Köppen_climate_classification | en.wikipedia.org/wiki/Climate_of_Los_Angeles

Journal Paper: Holden, Anna,. et al. A 50,000 year insect record from Rancho La Brea, Southern California: Insights into past climate and fossil deposition. Quaternary Science Reviews, 01 May 2017.

1.2 What is LA’s climate changing to?

This describes four attributes of  LA's emerging new so-called Dry Whiplash climate. Graphic.

A “Dry Whiplash” kind of climate describes LA’s emerging new climate classification. LA’s climate is quickening toward longer periods of total drought. Summertimes will have temps in 110s and 120s. Very hot weather will overtake much of what was LA’s amazingly pleasant Fall. The whiplash term comes from UCLA researchers describing LA’s surprisingly quick switches between long periods of exceptional drought and a brief period of super-voluminous rainstorms …then back to exceptional drought again.

LocalClimate.org description based on California’s Fourth Climate Assessment

1.3 LA’s current climate will soon be “departed.”

This shows the date when LA's current climate type will change over to a completely new climate. Graphic.

The time when LA’s climate will have completely changed is the city’s time of “climate departure.”

Climate departure is a kind of geo-temporal tipping point, or point of no return. For Los Angeles, time of departure will be around the year 2048. This is when Los Angeles will never again enjoy it’s comfortable Mediterranean climate. The LA region will exist in some brand new climate class, with its own set of patterns and characteristics.

In 2018, United Nations (UN) scientists made a shocking, historic warning: Devastating changes in climate will begin to manifest over the next few decades. The changes are happening in real time with the currently growing pace of carbon emissions.

UN scientists estimate that if people have, by the 2030s, cut way, way back on burning carbon fuels, a long-term climate apocalypse can be avoided – at least for a while. In a world with almost no new carbon added to the already warming atmosphere, eventually, the heat can dissipate. It is still possible, in the 2100s, for droughts to become less severe. Rain and water supplies can become more reliable, and people can consistently grow food outdoors.

Journal Paper: The projected timing of climate departure from recent variability. Mora, Camilo et al (2013). Nature. 502. 183-187. 10.1038/nature12540. 

Note: Time of Climate Departure is “the time after which all future years are predicted to be warmer than any year in the historical record [1865-2005].” 

Global Communication: The historic series of United Nations warnings about carbon emissions and the climate, beginning in 2018.

2. Climate Forecast for Los Angeles

The usual weather (the climate) of Los Angeles has been changing over the past several decades, and the change has been accelerating. 15 of LA’s 20 hottest years have all occurred during the 2000s and 2010s. Going forward, Angelinos will want to know something about LA’s trending climate situation.

2.1 How hot will it get in LA?

This shows the high temperatures that are expected in LA over the coming decades. Graphic.

A toasty 123˚ is the highest temp projected for Los Angeles (in LA’s Woodland Hills neighborhood) in upcoming decades – because of the currently increasing use of carbon-based energy.

Over the last several years, LA has had its warmest Summers on record. Recent years have brought record heat. People in LA’s Woodland Hills experienced a high temp of 117˚ during a 2018 heatwave.

The highest heat, with temps in the 110s˚ will be more common from the 2040s onward. 118˚ is the highest temp projected during this century for Downtown LA. Places like Hollywood and UCLA will reach a couple degrees cooler.

This shows LA's normal summertime high temperatures, which used to range between 75 and 82 degrees. Graphic.

During a heatwave in September 2018, Downtown LA had it’s highest temp so far: 113.˚ 82˚ is Downtown LA’s usual July high temp.

Scientists: Cal-Adapt (Geospatial Innovation Facility, University of California, Berkeley).   Method: CalAdapt Data Visualization Tool for Projections of  Extreme Heat under High Emissions Scenario 8.5 (“Business as Usual” /  “Growing Pace,” where Emissions continue to rise strongly through 2050 and plateau around 2099).   Data: LOCA Downscaled Climate Projections (Scripps Institution of Oceanography), Gridded Historical Observed Meteorological and Hydrological Data (University of Colorado, Boulder).  

Official Records: National Weather Service (NWS) and National Oceanic and Atmospheric Administration (NOAA) Climate Data for Los Angeles (USC Downtown campus), 1981 – 2010 averages   

Note: All LocalClimate.org temperature readings in the U.S. are shown in Fahrenheit F˚ degrees. Also Note: Daily High Temps (aka Daytime High Temps) are the highest temp reached on a given day, usually occurring in the late afternoon. 

2.2 This is How LA’s Climate is Changing

2.2.1 Los Angeles is trending toward longer, hotter Summertimes.

This shows how LA's summertime is getting much longer and much hotter as the decades go by. Extremely hot days are coming earlier in the spring and especially later in the fall. Graphic.

The 2020s – 2040s and 2070s – 2090s timelines here show LA’s emerging new heat season. Atmospheric scientists are calling this extended period of high heat a Super Summer.

In the 2070s, 2080s, and 2090s, usual daily high temps during an LA Super Summer will range from the 90˚s to the high 110s.˚ 

Away from LA’s Pacific Coast, heat is becoming more extreme, coming more often, and lasting longer. In recent decades, inland valleys of the Los Angeles region have been reaching temps above 90˚ during two months of the year. In the 2070s, 2080s, and 2090s, Los Angeles will have daily high temps above 90˚ during five months of the year.

Scientists: Cal-Adapt (Geospatial Innovation Facility, University of California, Berkeley).   Method: CalAdapt Data Visualization Tool for Projections of  Extreme Heat under High Emissions Scenario 8.5 (“Business as Usual” /  “Growing Pace,” where Emissions continue to rise strongly through 2050 and plateau around 2099).   Data: LOCA Downscaled Climate Projections (Scripps Institution of Oceanography), Gridded Historical Observed Meteorological and Hydrological Data (University of Colorado, Boulder).  

State Govt Report: Los Angeles Summary Report. California’s Fourth Climate Change Assessment (2018)  Hall, Alex; Berg, Neil; Reich, Katharine. (University of California, Los Angeles)  Publication number: SUM-CCCA4-2018-007

2.2.2 The new “Super Summer” in LA will be a season-long extreme heatwave.

This shows the growing number of heatwaves in Los Angeles as the decades go by. Graphic.

The 2070s thru 2090s timeline here shows a greatly extended heat season in LA.

Heatwaves are arriving earlier in the Summer and persisting further into the Fall. What used to be one or two occasionally hot days is often now a three or four day heatwave. Late-Summer / early Fall heat waves are merging together for several months of nearly uninterrupted high heat. As time goes on, heatwaves will be considered usual weather.

Scientists: Cal-Adapt (Geospatial Innovation Facility, University of California, Berkeley).   Method: CalAdapt Data Visualization Tool for Projections of  Extreme Heat under High Emissions Scenario 8.5 (“Business as Usual” /  “Growing Pace,” where Emissions continue to rise strongly through 2050 and plateau around 2099).   Data: LOCA Downscaled Climate Projections (Scripps Institution of Oceanography), Gridded Historical Observed Meteorological and Hydrological Data (University of Colorado, Boulder).  

Federal Govt Report: The Third National Climate Assessment (2014): Climate Change Impacts in the United States, Chapter 20: Southwest   [Garfin, G., G. Franco, H. Blanco, A. Comrie, P. Gonzalez, T. Piechota, R. Smyth, and R. Waskom] U.S. Global Change Research Program, pp. 462-486.,  doi:10.7930/J08G8HMN.

a huge crowd of joyous people out in the bright sun, waving at the camera

Change in when we do stuff: In the coming decades, community events like this late-September run/walk will have to be scheduled around LA’s ever-lengthening heatwave season. Or after midnight, when temps are more exercise-friendly. Photo by Homeboy 5K.

2.2.3 LA has already gotten warmer. Now it’ll be getting hotter.

This shows LA's high temperatures steadily rising as the decades go by. Graphic.

This is LA heating up: Los Angeles’ annual average high temp is steadily rising. At the current rate of carbon emissions and atmospheric warming, the annual high temp in LA will go past 100˚ sometime in the 2100s.

​To see long-term trends in the changing atmosphere, and to account for the variability of weather from year to year, climate researchers prefer looking at climate data over a 30-year span. But here, even at 10-year intervals, a steady warming trend can be seen over the LA area. Temps in Los Angeles have already been, and will keep on rising.

Scientists: Cal-Adapt (Geospatial Innovation Facility, University of California, Berkeley).  Method: CalAdapt Data Visualization Tool for Projections of  Extreme Heat under High Emissions Scenario 8.5 (Growing Pace / Business as Usual scenario) where Emissions continue to rise strongly through 2050 and plateau around 2100), and Low Emissions Scenario 4.5 (Quickly Reduced / Carbon Mitigation scenario) where emissions peak around 2040, then decline.)  Data: LOCA Downscaled Climate Projections (Scripps Institution of Oceanography), Gridded Historical Observed Meteorological and Hydrological Data (University of Colorado, Boulder). 

Note: The Annual Average High Temp is the sum of the high temps of each day of the year, divided by 365. Even the high temp of each Wintertime day is part of the average. 

2.2.4 LA’s rain pattern is changing.

kids in raincoats playing with a shopping cart in a flooded parking lot

Rainfall in Los Angeles is not changing much in terms of amount, but in when and how it rains.  Rain is switching between extremes of not enough and way too much. Extremely tenacious droughts are being extinguished by increasingly brutal rainstorms.  

That car is totalled: All the rain that would have fallen on Los Angeles over the last several months (or even several years) finally comes – all within a very intense several days. Photo: Associated Press

Journal Paper: Swain, D. L., B. Langenbrunner, J. D. Neelin, and A. Hall, “Increasing precipitation volatility in 21st-century-California,” Nature Climate Change, doi: 10.1038/s41558-018-0140-y, 2018.

2.3 Why is LA warming differently in three different locations?

​The usual weather (climate) over the sprawling Los Angeles landscape is like real estate. It’s all about location. Depending on how close you are to the ocean coast, or to the inland desert …or if you’re up in the hills or down in the Valley – you’ll experience variations in how warm it gets and for how long. The number of hot days each year (days with a high temp above 90˚) over the upcoming decades depends on where you are in the city. Some places in LA will bake for longer periods of time than others.

This set of graphics shows how your location in LA can make a difference in how intensely the local climate is changing. Graphic/
This shows how Los Angeles International Airport's will have a more gradual rise in the number of hot days because it is so close to the ocean. Graphic.

The cold Pacific Ocean water cools the atmosphere above it – including the air several miles inland from the coast. Los Angeles International Airport (LAX) is situated on the coast, so temps go past 90˚ only a few days each year. LAX will stay relatively cool (relative to inland areas of LA) most of the time until the 2050s.

This shows how LA's San Fernando Valley will have many more hot days because it is farther away from the ocean. Graphic.

The San Fernando Valley  (here, for example, in LA’s Northridge neighborhood) is blocked by hills and sits well enough inland that it hardly benefits from the ocean’s cooling influence.  Summer temps here tend to run several degrees warmer than other parts of the city, and people experience much more time in warmth. By the 2050s, under the “Growing Pace” carbon emissions scenario, Northridge’s number of days each year with temps over 90˚ will double from those of the 1990s – from 64 days to 127 days. 

This shows that LA's Hollywood neighborhood will have far more hot days in the future than it does now. Graphic.

Hollywood doesn’t get quite as baked as the San Fernando Valley, but it’s already increasing number of very warm days will likewise surge.  Two weeks above 90˚ now, four weeks in the 2050s, and two months in the 2090s:  This is a quadrupling of very warm days each year within the period of an average person’s lifetime.

Scientists: Cal-Adapt (Geospatial Innovation Facility, University of California, Berkeley).  Method: CalAdapt Data Visualization Tool for Projections of  Extreme Heat under High Emissions Scenario 8.5 (Growing Pace / Business as Usual scenario) where Emissions continue to rise strongly through 2050 and plateau around 2100), and Low Emissions Scenario 4.5 (Quickly Reduced / Carbon Mitigation scenario) where emissions peak around 2040, then decline.)  Data: LOCA Downscaled Climate Projections (Scripps Institution of Oceanography), Gridded Historical Observed Meteorological and Hydrological Data (University of Colorado, Boulder).