Los Angeles heat wave may extend to last weekend of August
More days of extreme heat are in store for Los Angeles, much of Southern California and the interior southwestern United States.
People driving on a notoriously hot stretch of Interstate 15 between Los Angeles and Las Vegas are urged to take precautions during this intense August heat wave.
The major heat wave in progress over Southern California is forecast to continue nearly to the end of August as a dome of high pressure over the interior Southwest extends toward the Pacific Coast.
In the Los Angeles area, a heat wave occurs when high temperatures reach or exceed 90 degrees Fahrenheit for at least three consecutive days.
So far, the highest temperature during the current heat wave in the city core has been 98 degrees on Sunday, Monday and Wednesday, which matched the high mark of March 17, set during the record-setting late-winter heat dome. Temperatures on Thursday and Friday this week should bring high temperatures in the middle to upper 90s.
"At this time, we are projecting a 12-day stretch with highs of 90 or greater," AccuWeather Meteorologist Elizabeth Danco said.
One of the most intense heat waves in Los Angeles was in 1955 when high temperatures reached or exceeded 100 degrees from Aug. 31 to Sept. 7. The hottest day on record was on Sept. 27, 2010, when temperatures reached 113 degrees.
The current heat wave will not bring the extreme heat of either of those years, but it will set some daily record highs and perhaps make up for it in terms of duration. Records dating back to the early 1930s will be challenged.
"Downtown Los Angeles has had 90-degree temperatures consistently since Aug. 18 and is likely to continue to experience the same through Aug. 29," Danco said. "That's 12 straight days."
During stretches of hot weather, ocean air typically spreads inland at some point, marking an interruption to 90-degree heat. It takes a sufficient offshore breeze to prevent that from occurring, but the ongoing forecast stretch could do just that.
Temperatures in downtown Los Angeles will be 10-15 degrees above the historical average. Farther inland, such as around Palm Springs, California; Las Vegas and Phoenix, highs will be 4-8 degrees above the historical average, with temperatures reaching the 110s most days into this weekend.
Warmth will be felt on the beaches as well, with highs forecast to be at or above 90 degrees at Long Beach, California, into Saturday. San Diego will escape the worst of the heat with highs mainly in the 80s. However, humidity levels will be higher when compared to L.A.
People are urged to stay hydrated during the heat wave and avoid prolonged strenuous activity during midday and afternoon hours, when the sun's intensity is greatest. Caution is strongly advised when using open flames and power equipment due to dry brush and extreme temperatures. Sparks can induce a rapidly spreading wildfire under these conditions.
"A storm forecast to push into the Northwest this weekend should break the string of hot days and create more of a penetrating breeze from the Pacific across the Interstate 5 corridor of Southern California," AccuWeather Senior Meteorologist Tom Kines said.
Heading to the beach? Watch those waves
People heading to the beaches should exercise some caution in the surf into next week, as new tropical activity brewing off the coast of Mexico could send large swells toward the California coast.
These will show up as occasional large breakers and perhaps even some sneaker waves.
"Afternoon sea breezes will offer some relief through Friday for those who choose not to go into the water at the beach," Kines said.
LA heat wave to reach 'extreme' on AccuWeather HeatWave Counter and Severity Index™
In Los Angeles, the heat wave through Aug. 29 is forecast to be extreme on AccuWeather's HeatWave Severity Index™.
“AccuWeather’s unmatched trove of historical weather data has allowed us to go back and quantify past heat waves for many of the major cities,” said Jonathan Porter, AccuWeather’s Chief Meteorologist and Senior Vice President, Weather Content and Forecast Operations.
Heat waves are defined as three or more consecutive days when the temperature exceeds a threshold that varies with each location's climate. For downtown Los Angeles, that temperature mark is 90 degrees.
“With the AccuWeather HeatWave Counter and Severity Index™, we count the number of heat waves within the summer and compare them to previous summers, providing helpful information that exclusively places heat waves and their impacts into historical context, so people can better plan their activities, enhance their safety and improve their wellness,” Porter explained.
Want next-level safety, ad-free? Unlock advanced, hyperlocal severe weather alerts when you subscribe to Premium+ on the AccuWeather app. AccuWeather Alerts™ are prompted by our expert meteorologists who monitor and analyze dangerous weather risks 24/7 to keep you and your family safer.
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