LOS ANGELES >> California was in a state of emergency today 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.

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.

>> RELATED: Firefighters battle California wildfires amid searing heat

“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 this 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.

Rolling blackouts “are a possibility but not an inevitability” during the current heat wave, said Elliot Mainzer, president and CEO of the California Independent System Operator.

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.

On Skid Row in downtown Los Angeles, where thousands of homeless people live on the street without access to air conditioning or refrigerators, many of the cooling centers they’ve relied on in past years remain closed due to COVID-19 restrictions.

The sight of a half dozen volunteers wheeling carts full of ice cold water bottles was a welcome sight.

“It’s hotter than heck out here,” said Dan, a homeless man huddled with others in the shade of a building. “All of us have to stay outside here, look for shade and count on people coming by with water. … These five days are going to be rough.”

Temperatures Wednesday soared as high as 112 degrees (44.4 Celsius) in Los Angeles’ San Fernando Valley neighborhoods. Anaheim, home to Disneyland, had an all-time August record of 106 (41.1 Celsius). Death Valley fried at 123 (50.5 Celsius).

The heat hung on throughout the night, staying in the 80s in parts of Los Angeles and the 90s in the foothills and valleys, including an overnight temperature of 96 degrees (35 Celsius) in Tuna Canyon near Malibu, according to the National Weather Service.

“The lack of overnight relief is one reason this #HeatWave (is) DANGEROUS,” the weather service tweeted.

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 Office of Emergency Services positioned fire crews in strategic locations in Southern California and the San Joaquin Valley, based on humidity and wind forecasts.

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.

They quickly burned several thousand acres and shut down highways. Eight firefighters battling the Castaic blaze were treated for heat-related problems and six of them were taken to the hospital, Los Angeles County Fire Department Deputy Chief Thomas Ewald said.

“Wearing heavy firefighting gear, carrying packs, dragging hose, swinging tools, the folks out there are just taking a beating,” he said.

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 drought that have affected much of the West.

Anticipated imports of hydropower from the Pacific Northwest and energy from the desert Southwest dried up because warmer weather in those regions had driven up demand there, Mainzer said.

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.