Autumn winds are kicking up in Northern California again this week, increasing the risk of wildfires and causing Pacific Gas & Electric Co. to shut off power to about 361,000 customers in the weather-weary region.

As a preventative measure in the face of Diablo winds and single-digit humidity levels, parts of 36 counties and 17 tribal communities are losing power, according to PG&E.

“PG&E is calling a [public safety power shutoff] due to a significant, offshore wind event starting Sunday that is forecast to have the driest humidity levels and the strongest winds of the wildfire season thus far, that together create high risk of catastrophic wildfires,” PG&E said in a statement Sunday.

California

60,000 ordered to evacuate in Orange County as wind-driven brush fire grows rapidly

PG&E cuts power to 361,000 as fierce Diablo winds blow through Northern California

California

60,000 ordered to evacuate in Orange County as wind-driven brush fire grows rapidly

The Silverado fire broke out in Orange County on Monday morning amid conditions forecasters were calling the most dangerous fire weather of the year.

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Strong Diablo winds are expected in much of the area surrounding the Sacramento Valley, most of the Sierra, parts of southern Kern County and the mountainous regions of the Bay Area, including the Santa Cruz Mountains.

Red flag warnings are in place for most of Northern California. A warning for the North Bay Mountains and the East Bay Hills is in place through Tuesday afternoon, according to the National Weather Service, while another warning for the coastal regions, Santa Cruz Mountains and the lower valleys expires at 11 a.m. Monday.

Winds are around 40 to 60 mph in much of the area, said National Weather Service meteorologist Anna Schneider. A 94-mph gust blew through part of Tahoe overnight, and Mt. Saint Helena saw gusts at 89 mph, according to the weather service.

Strong winds continue early this morning across #NorCal. The strongest winds are occurring over the higher elevations of the northern #SierraNevada where gusts over 70 mph have been reported. Gusty winds will persist into midday with critical fire weather conditions. #CAwx pic.twitter.com/7JUcdq0kJS

— NWS Sacramento (@NWSSacramento) October 26, 2020

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Relative humidity is hovering in the 20s and below across the Bay Area, with at least some areas dipping to 5%, forecasters said.

“It’s been very dry,” Schneider said. “We’ve been kind of lucky here. We haven’t had any major fires starting overnight in our area. But it’s certainly dry enough.”

A few small fires did ignite, but emergency responders were able to snuff them out before they grew, she said. California Department of Forestry and Fire Protection units for San Mateo and Santa Cruz reported downed trees in Half Moon Bay.

Once the fierce offshore winds taper off Tuesday, lower temperatures are expected to roll in, making for cooler nights in parts of the Bay Area, Schneider said. Dry air and clear skies have already caused temperatures to plummet in parts of the valley. Forecasters say the marine layer should return later in the week, bringing mild weather.