SAN DIEGO — Scorching heat in the West produced record temperatures Friday and is expected to linger through the weekend in some regions.
Hollywood Burbank Airport in the Los Angeles area matched its all-time high temperature with a reading of 114, according to the National Weather Service in Oxnard, California, which set its own record high for the date of 99.
Downtown Los Angeles tied its record high for the date at 111, it said. Santa Ana (113) and Newport Beach (95) in Orange County and Ramona (114) in San Diego County set new records for the date, weather service numbers show.
The weather service office in Phoenix said the 93-degree morning low temperature recorded at Sky Harbor International Airport was the warmest for any September day on the books.
In Yuma, Arizona, where records date to 1878, the desert town posted a high of 109 on Friday and thus bested its last streak of consecutive days with highs above 100 degrees, reaching 100 days of triple-digit highs this summer, the Phoenix office said.
Death Valley reached 119 on Friday, but it wasn't a record, according to the weather service. In the Pacific Northwest, multiple inland locations, from Spokane, Washington, to Coeur d'Alene, Idaho, recorded temperatures in the 90s, according to the weather service's Spokane office.
Forecasters initially had heat alerts associated with the wave lasting through Friday, but some forecasters have extended them through the weekend and even Monday.
NBC News forecasters say 50 million people will be covered by heat alerts through the weekend. The National Weather Service's alerts include a top level excessive heat warning, when conditions pose a significant threat to life, and an excessive heat watch, when temperatures will rise but timing is unclear.
Excessive heat warnings cover an area from Long Beach, California, nearly to San Luis Obispo County, according to weather service information and maps. Excessive heat warnings for much of the rest of Southern California, including San Diego, Orange, Riverside, and San Bernardino counties, were to expire at 8 p.m.
Such warnings for the eastern half of Oregon were expected to expire at 10 p.m. Friday.
The California Independent System Operator, which manages California's electricity grid, issued "restricted maintenance operations" requests to utilities that urged them to avoid scheduled maintenance from noon to 10 p.m. Wednesday through Friday.
The requests seek to ensure that no utility provider is off the grid during the high demand that comes with a heat wave. Otherwise, demand remained lower than capacity Friday, and voluntary conservation efforts under a program known as FlexAlert were not expected.
"The grid is stable and no FlexAlerts are planned," Cal-ISO spokesperson Vonette Fontaine said by email.
A high pressure system over the desert Southwest is warming air and blocking the cool influence of the Pacific throughout the West. The weather service's coast-to-coast forecast states the system will remain until Saturday but will start to move east Sunday.
"Temperatures should decrease across the West Sunday into Monday as the ridge shifts east over the Central United States, and scattered light showers and storms will be possible as a weak upper level wave moves across the region," it said in a forecast discussion on Friday.
Thunderstorms produced by a lingering storm front were expected to continue to soak states along the Gulf Coast this weekend, with 5 million people from east Texas to northern Florida covered by flood alerts, NBC News forecasters said.
Forecasters in parts of Southern California, meanwhile, said heat would linger through Monday and possibly longer despite a minor storm front moving in over the Pacific Northwest.
The high pressure system is pushing back at the ocean’s normally cool influence as it generates wind that travels from east to west and warms the air as it travels from higher elevations, including mountains, to the coast.
And a minor rain front that could provide some relieve to parts of the West is too far north to do so for Southern California, federal forecasters said.
"This area the offshore flow does appear to linger," said weather service meteorologist Joe Sirard. "We're continuing the hot weather over this area."
The light at the end of the tunnel for Southern California is the possible return of onshore winds, with the cold Pacific blowing on the land and cooling it off, come Wednesday, Sirard said.
“We might be slightly below normal temperature by then,” he said.
The U.S. Environmental Protection Agency says heat waves have become more frequent, longer, and more intense in recent years, and that these elements compose an "indicator" of climate change or global warming.
The European Union's Copernicus Climate Change Service said the summer of 2024 was the hottest on record for the Northern Hemisphere, surpassing the last hottest summer — last year's.
