Heat advisory issued for parts of Southern California as temperatures soar

Heat wave grips Southern California

Southern California is bracing for its hottest week of the summer so far, with the National Weather Service warning of record-setting temperatures across the region. A bulletin from the agency said widespread highs will run 6 to 12 degrees above average, prompting excessive heat warnings. "This will be the hottest week of the summer so far," the bulletin reads, adding that overnight temperatures will also be warm, with many areas set to break record high minimums.

The heat advisory issued by the National Weather Service took effect at 10 a.m. Saturday and will remain in place until 8 p.m. Monday, covering Inland Orange County, the Riverside mountains and valleys, and the San Bernardino valleys. Forecasters also warned of extreme highs of 100 to 110 degrees in "all areas" five to 10 miles inland, with triple-digit temperatures expected by Tuesday or Wednesday and lingering through Saturday.

Forecast details and regional impacts

In the Los Angeles area, temperatures are expected to stick in the mid to high 90s for several days, while inland communities could reach between 107 and 112 by midweek. Monday's highs are forecast to be about 1 or 2 degrees cooler than Sunday in most communities, but they're set to jump back up on Tuesday, according to CBS LA meteorologists. Triple digits were forecast in the Inland Empire for Tuesday, with inland parts of Orange County threatening to cross the 100-degree threshold.

Downtown Los Angeles is expected to see a high of 97 degrees by Saturday afternoon, while Malibu will be close to 90 with a high of 88. Burbank could hit 99 degrees on Sunday, and Hemet is expected to reach 104 on Saturday. Santa Clarita and surrounding areas are also forecast to see triple digits this weekend.

The heat is expected to stick around through most of next week. The LA and Orange County metro areas can expect 90-degree heat, while the valleys could see a possible high of 106 next Friday.

The National Weather Service in Oxnard said Sunday evening that temperatures will hit triple digits by Tuesday or Wednesday and remain elevated through Saturday. "The northerly shift in the flow means that the hottest conditions will not be in the desert, but in the coastal valleys," forecasters warned. The agency warned of a high risk of heat-related illness and urged residents to prepare for "a long duration heat event, during which several daily records will likely be broken." Even beach towns are forecast to see highs in the 90s.

Hottest week of the year for many

"For much of L.A., this will likely be the hottest [week] of the year," said Ryan Kittell, a meteorologist with the National Weather Service in Oxnard. "It will be warm Monday, then really crank up Tuesday. ... In the valleys, we're looking at anything between 100 and 110." Along the coast, Kittell said, expect "highs between 80 and 90, even in the beach areas."

Between Sunday and Wednesday, forecasters said there is a 30% to 40% chance of highs of at least 110 degrees in the San Fernando Valley and a 50-50 chance of highs of at least 100 degrees in downtown LA. In downtown Los Angeles, highs hit 96 degrees on Sunday.

A long-term forecast from the weather service predicted little relief, asking: "The only real question for the [Wednesday] through [Friday] forecast is: will it be very hot or extremely hot?"

The agency also said it was "very likely that almost the entire forecast area" would be under heat advisories or extreme heat warnings by Wednesday.

San Diego County under extreme heat watch

Coastal San Diego County will experience "dangerously hot conditions" this week when a high pressure system is expected to lift temperatures into the mid-80s at some beaches and up to 93 a couple of miles inland, says the National Weather Service, adding that treacherous surf is expected in many areas. An extreme heat watch will be in effect from 10 a.m. Tuesday to 8 p.m. Friday from Oceanside to Chula Vista.

The conditions will be even worse across inland valleys and foothills, notably in Ramona, which could reach 110 degrees late in the week. Areas near Borrego Springs are expected to hit 115. San Diego's daytime high will dip a bit on Monday, then increase on Tuesday and intensify as the week goes along, peaking on Thursday and Friday.

Overnight temperatures in San Diego County will be 5 to 7 degrees higher than usual because the ocean is unseasonably warm, making it difficult for many people to sleep, forecasters said. The heat wave is arriving during a month in which the daily high temperature in San Diego has been above normal every day.

The weather service also is forecasting a 4- to 5-foot southerly swell to move into the area Wednesday and Thursday, leading to elevated surf for the south-facing beaches of northern San Diego County and Orange County.

The role of warm nights and ocean heat

While daytime heat has been "pretty typical" for summer, in the words of Mike Wofford, a meteorologist with the National Weather Service in Oxnard, experts point to several factors that have made the season feel unusually oppressive. Nighttime temperatures remain stubbornly high, and it's been broiling along the coast, which typically offers a cooler respite.

"It's been an extraordinarily, arguably record-breakingly, warm summer at night," said climate scientist Daniel Swain, "but not so much in terms of the hottest daytime temperatures, which is what everybody always talks about in terms of how hot it's been."

Swain, an associate researcher at University of California Agriculture and Natural Resources, analyzed Southern California climate data from June 23 to Aug. 23. He found that Torrance recorded its fourth-warmest period and LAX its fifth-warmest for average temperatures, but the warmest on record for nighttime temperatures in Torrance and third-warmest at LAX. Hotter nights can prolong the stress that heat places on the human body by depriving people of a chance to recover, increasing the risk of heat-related illness, he noted.

The latest heat wave continues what's proving to be a sweltering summer globally as temperatures rise because of climate change, with last month tying 2024 as the warmest July since record-keeping began in 1850, per the National Oceanic and Atmospheric Administration.

Safety advice and impacts

The National Weather Service urged residents to "drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors" throughout the week. LA County has a website with resources to help residents during extreme heat, including cooling centers.

CBS LA has issued a Next Weather Alert across the region through Tuesday due to extreme heat, and a Next Weather Watch is in place through Friday, which could be elevated to an alert if suitable.

The heat has already had real-world consequences. A power outage in Long Beach affected 22,660 customers, starting at 6:40 p.m. Sunday, according to SCE spokesperson David Eisenhauer. Residents described the ordeal: Sumouni Basu said she was unable to access her car and her cat was sluggish, while Becky Sudbrink said she used more air conditioning than she'd like due to the heat.

In Death Valley National Park, a 68-year-old French traveler died on Aug. 17 after his car broke down on a 116-degree day. The park had a high of 121 degrees, with projections of 119-120 through Friday.