Brutal heat wave to hit California and sizzle past Labor Day

California was in a state of emergency Thursday as a brutal heat wave brought the threat of power outages and wildfires.

Temperatures will continue to reach triple digits in many areas of the state through Labor Day, forecasters said, prompting concerns that people will turn up the air conditioning and strain the state’s electrical grid.

"It's going to be a scorcher to at least about Tuesday," said KTVU meteorologist Rosemary Orozco. Inland temperatures will peak above at 110 degrees on Monday. 

Gov. Gavin Newsom on Wednesday declared an emergency to increase energy production and relaxed rules aimed at curbing air pollution and global warming gases. He emphasized the role climate change was playing in the heat wave.

"All of us have been trying to outrun Mother Nature, but it’s pretty clear Mother Nature has outrun us," Newsom said. "The reality is we’re living in an era of extremes: extreme heat, extreme drought — and with the flooding we’re experiencing around the globe."

Newsom’s declaration followed a "Flex Alert" call for conservation on Wednesday afternoon and again for Thursday afternoon by the California Independent System Operator, which oversees the state’s electrical grid.

In August 2020, a record heat wave caused a surge in power use for air conditioning that overtaxed the grid. That caused two consecutive nights of rolling blackouts, affecting hundreds of thousands of residential and business customers.

Cooling centers were being opened across the state and officials encouraged people to seek comfort at public libraries and stores — even if just for a few hours to prevent overheating.

In Contra Costa County, Walnut Creek issued a notice that Lime Ridge, Acalanes Ridge and Shell Ridge Open Space areas will be closed through Tuesday because of high temperatures. 

Temperatures could be 10 to 20 degrees above normal in some regions during the day, with little relief overnight. Excessive-heat warnings were in effect for Southern California and up into the Central Valley. The heat was expected to spread into Northern California and could top 100 degrees in San Francisco Bay-area hills, although San Francisco probably would only have highs in the 70s and 80s, forecasters said.

The National Weather Service warned of an increased risk of wildfires. The California Department of Forestry and Fire Protection planned to stage fire crews in strategic locations, based on humidity and wind forecasts, said Mark Ghilarducci, director of the Office of Emergency Services.

On Wednesday afternoon, wildfires broke out in bone-dry brush in rural San Diego County and Castaic in the Santa Clarita Valley north of Los Angeles, where a mobile home park was evacuated.

In the North Bay, PG&E says the cause of Wednesday's power outage that impacted some 6,000 customers in Healdsburg, Geyserville, and Cloverdale, was likely a damaged wooden power pole that appeared to have been hit by a vehicle. The pole in Cloverdale carried transmission lines to a substation that was in a high-risk fire area, but fortunately did not spark a fire.

The risk of fire also could increase over the Labor Day weekend when crowds are expected to descend on wilderness areas to camp, hike or fish and a spark or an ember from an untended fire could set brush ablaze, authorities said.

Meanwhile, California’s power concerns come in the midst of rising temperatures and a drought that have affected much of the West.

Despite more than 160 projects to increase power supply and storage by 4,000 megawatts after outages two years ago, the the state’s power supply was partly crippled by the impact of the ongoing drought that has sapped a significant share of the state’s hydropower production as reservoir levels drop.

Newsom’s order allows use of backup diesel generators to put less strain on the system and won’t require ships at port to plug into onshore electricity sources. The move is expected to increase air pollution, but Karen Douglas, the governor’s senior energy adviser, said the priority was to keep the lights on.

Newsom has proposed extending the life of the state’s last operating nuclear power plant by five years to maintain reliable power supplies in the climate change era. The proposal would keep Pacific Gas & Electric’s Diablo Canyon Nuclear Power Plant running beyond a scheduled closing by 2025.