Red flag warning in California could lead to power outages

SAN FRANCISCO – A “vicious wind” is blowing across Northern and coastal California and could lead to preemptive power shutoffs for nearly 30,000 homes in 30 counties as early as Thursday, the local utility warns.

To protect against accidental fires, Pacific Gas & Electric sent notices to potentially affected customers throughout much of the state's northern and central coastal region, informing them that power to lines to affected areas may need to be shut off to deal with the possibility to limit electrical sparks.

The National Weather Service issued a “Red Flag Warning” for Northern California from Thursday night through Saturday night, meaning “critical fire weather conditions are likely or imminent.” Officials are warning potentially affected residents to have an emergency plan in case a fire breaks out near them.

“Diablo winds” is the local name for hot, dry winds from the northeast that sometimes strike the San Francisco Bay Area and the central coast of California, particularly in the spring and fall. The Southern California term for a similar phenomenon is the Santa Ana wind.

Studies have found that climate change increases the likelihood of wind-driven extreme wildfires in the fall.

“The winds are coming from the north, not the typical sea breeze off the water, which would be cooler,” said Roger Gass, a meteorologist at the National Weather Service's San Francisco Bay Area office.

These conditions make the area susceptible to easier fire outbreak and possible explosive fire spread.

Previous fires caused by Diablo winds included the 1991 Oakland Hills firestorm, which killed 25 people and started with a small fire on private property. The 2017 Tubbs Fire in Napa County killed 22 people and burned 36,000 acres. It was caused by a private electrical system. The 2019 Kincade Fire in Sonoma County started when a cable broke on a PG&E transmission tower.

Areas potentially at risk include cities such as Napa, Berkeley, San Jose and Big Sur.

Warm temperatures, extremely dry vegetation and strong winds of 25 to 35 mph, with some gusts up to 65 mph, are a recipe for a possible wildfire.

“This could be the highest fire danger so far this year,” Daniel Swain, a climate scientist at the University of California, Los Angeles, said on X.

Northern and central California had a long, hot and very dry summer, with some areas seeing almost no rain since July 1, according to Golden Gate Weather Services.

“The fuels are critically dry,” Gass said. “If it had rained, we wouldn’t be worried.”

This means there are no campfires, fire pits or grills. Vehicles are also prohibited from driving off-road where they could start a grass fire. Residents are warned against using lawnmowers or other power tools outdoors and are asked to double-check trailer chains to ensure they are not dragging on the road, as the friction can cause sparks.

As the California Department of Forestry and Fire Protection puts it: “One less spark, one less wildfire.”

“That’s how most fires start, they’re caused by people,” Gass said. The National Parks Service estimates the number of human-caused fires to be 85%.

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