California heat wave elevating fire risk and threat of rolling power outages

Article Republished By Javier Troconis

State power officials also urged people to conserve electricity and raised the specter of rolling power outages.

Temperatures in the outer East Bay, including Walnut Creek and Livermore, were headed to forecast highs above 90 on Wednesday. In Vacaville, the temperature surpassed 90 around noon and was expected to reach 98 degrees. Most of the rest of the Bay Area remained cooler — for the moment.

Hotter weather was expected to arrive on Thursday, with temperatures increasing through the Labor Day weekend, reaching well over 100 degrees by Sunday and Monday in the East Bay hills, Santa Cruz Mountains and North Bay mountains, according to Chronicle meteorologist Gerry Díaz. Temperatures could reach or surpass 105 in Livermore and Concord, according to forecasts.

The National Weather Service issued an excessive-heat warning Wednesday morning, predicting dangerously high temperatures in the interior regions and higher elevations while coastal areas remain cooler. San Francisco was expected to stay in the 70s along the coast and climb into the 80s inland, thanks to ocean breezes. The heat warning takes effect at 11 a.m. Saturday and lasts through 9 p.m. Tuesday.

State energy officials and Gov. Gavin Newsom urged Californians to reduce their electricity use between 4 p.m. and 9 p.m. on Wednesday and Thursday to ease the strain on the power grid caused by high temperatures and air conditioning use. More of those requests, known as Flex Alerts, were possible through the Labor Day weekend as the worst of the heat wave hits.

Cutting back on electricity use aims to prevent the potential for rolling power outages, which Elliot Mainzer, president and CEO of California Independent System Operator said in a news briefing, “are a possibility but not an inevitability.”

At a Wednesday afternoon news briefing, Newsom advised people leaving home for the weekend to turn their thermostats up to 85 degrees to give their air conditioning and the state’s power grid a break. Those staying home should help out by raising thermostats to 78 degrees between 4 p.m. and 9 p.m., the Flex Alert period. He also advised people to “pre-cool” their homes and charge electric vehicles before 4 p.m.

“We’re used to record-breaking temperatures, maybe a day or two,” he said, “but this is an extended period. As a consequence, it’s going to require us to extend our thinking and our imagination … to keep people healthy, keep people safe and to make sure that we are working to address our energy needs and energy reliability.”

Fire danger, originally expected to be moderated by the near absence of wind, picked up as the forecast changed to indicate very low humidity and light Diablo winds in addition to the expected extreme temperatures.

Add to those factors the crowds expected to travel over the holiday weekend, which many regard as the unofficial end of summer, many hauling trailers, camping and spending time outdoors, and it spells an increased risk of wildfire.

“We’re looking at elevated fire danger throughout the state,” said Jon Heggie, a Cal Fire captain. “With high temperatures, low humidity, low fuel moisture and a lot of dead fuel, any fire that starts could spread quickly.”

Fortunately, the forecast calls for only light Diablo winds — the dangerous, often high winds from the north — during the heat wave, Díaz said. With the winds expected to reach only 10-15 mph, he said, “they won’t pose much of a risk of fanning the flames.”

Humans, however, could. With crowds expected to pack highways, hiking trails and campgrounds, the chance of a stray spark igniting a vegetation fire that could grow into a wildfire increases.

“Even a small spark, from a cigarette butt even, could ignite a fire,” Díaz said.

Cal Fire officials advise folks enjoying the outdoors to heed local restrictions on campfires. Many areas prohibit wood or even charcoal fires whether in fire pits or grills. They also advise people towing trailers to make sure chains are not hitting the pavement, which can create sparks.

Cal Fire expects to bring on extra firefighters over the weekend to be ready to quickly attack any wildfires that ignite, Heggie said. As he has repeatedly, Newsom linked the power grid problems and increased fire dangers to climate change.

“For years and years and years, we have been trying to outrun Mother Nature,” he said, “but it’s pretty clear that Mother Nature has outrun us. The reality is we’re living in an era of extremes: extreme heat, extreme drought.

“The hots are getting a lot hotter. The drys are getting a lot drier. We’re living, again, in an age of extremes. I don’t have to explain that to anybody in particular living in California.”

Michael Cabanatuan (he/him) and Claire Hao are San Francisco Chronicle staff writers. Email: and Twitter: @ctuan and @clairehao_

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