A four-day heat wave reaches its sizzling zenith Saturday, when Death Valley-like temperatures will bake Southern California, ratcheting up concerns about wildfires and turning outdoor activities into sweltering chores.
The spike in temperatures comes during what is usually the beginning of the Santa Ana season, when gusting winds can dry out already desiccated vegetation and whip small fires into monsters. Saturday could see temperatures in the triple digits across the region, with some places baking under heat as high as 106 degrees.
"This is not a good preview of coming attractions," said William Patzert, a climatologist for the Jet Propulsion Laboratory in La Cañada Flintridge. "Triple-digit temperature, single-digit humidity and gusty breezes — that's a formula for misery and fires."
If there's an upside, it's that this weekend's winds will not be too strong, said Patzert, calling them "Santa Ana Lite." But they're strong enough to play a starring role in the Southland heat wave.
A high-pressure system combined with weak Santa Ana winds have generated the hot weather, said Stuart Seto of the National Weather Service. The winds sink as they blow through the mountains, then compress and warm up as they move toward the coast, he said. So in addition to heating the area, the winds block the sea breezes that usually cool coastal communities.
On Thursday, places such as Oxnard and Santa Maria experienced temperatures that broke records almost 70 years old. The Long Beach Unified School District had to shorten school days on Thursday and Friday because most of its campuses do not have air conditioning. Los Angeles Unified canceled all outdoor activities and sports practices in the San Fernando Valley.
The hot temperatures, low humidity and windy conditions prompted the U.S. Forest Service to implement 24-hour firefighter staffing as officials issued red flag warnings across the Southland.
Local fire officials are preparing for a potentially rough weekend. Los Angeles Fire Department Capt. Jamie Moore said firefighters have been warned to be ready for deployment at a moment's notice, and to be prepared to be on fire lines for multiple days.
On Thursday morning, the department deployed about 60 additional personnel to stations in areas prone to wildfires, Moore said. He said the department expects that extra staffing to remain in place at least through Saturday.
"Everything is getting in alignment where explosive fires can occur," Moore said.
Forecasters expect that places such as Woodland Hills, Pasadena and downtown L.A will see temperatures of 106, 104 and 101. Even Los Angeles International Airport, near the coast, is expected to reach 96 degrees.
The oppressive temperatures are forcing organizers of some outdoor events to take precautions this weekend.
At the Vegan Oktoberfest in Santa Monica, organizers are setting up "tons of shade," misting fans and water booths, said event founder Jill Ryther. Officials expect more than 3,000 patrons to fill up on food and beer.
In Manhattan Beach, the Old Hometown 10K is scheduled to begin at 7:30 a.m. Saturday. Race director Rachel Judson said she hopes all participants will be off the course by 9:30 a.m., before temperatures peak. She said the 37th running will be the hottest ever.
"We're making sure that our water stations are all well-staffed," Judson said. "People have dreaded" the early start time in the past, "but this year they're embracing it."
Angelenos are just weeks removed from an earlier blast of blistering heat that led to the opening of cooling shelters and fueled a brush fire in Orange County that forced canyon residents to evacuate.
Patzert said periodic heat waves are common in September and October; temperatures will rise sharply for a few days, then fall sharply back to more tolerable levels, he said.
On Sunday, temperatures will begin to drop by as much as 10 degrees in some areas. And by Wednesday, the region will return to more typical weather: mid-70s at the beaches and lower 80s inland.
"We're living in a warmer world, so we should expect that daytime and nighttime temperature records will tumble," Patzert said. "In terms of wardrobe ... you don't want to retire your cargo shorts and Hawaiian shirts quite yet."