(CBS SF) – Pacific Gas & Electric Co. announced that 37,000 customers in 15 counties will have their electricity turned off in the latest round of Public Safety Power Shutoffs (PSPS), including more than 4,000 Bay Area customers.

The utility said Wednesday that crews will begin to shut off power starting Wednesday evening into Thursday morning over the risk of potential wildfires.

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“PG&E is calling a PSPS due to a high-wind event combined with low humidity and severely dry vegetation, that together create high risk of catastrophic wildfires,” the utility said.

The National Weather Service has issued a Red Flag Warning for the North Bay Mountains, East Bay Hills and Santa Cruz Mountains from 10 p.m. Wednesday through 8 a.m. Friday.

The utility said recent changes in the forecast has decreased the number of affected customers by 31 percent.

In the Bay Area, about 4,200 customers in Alameda, Contra Costa, Napa, Santa Clara and Sonoma counties will be impacted. Power is not expected to be shutoff for affected Bay Area customers until the early morning hours.

PSPS Bay Area Impacts (Number of Customers & Estimated Shutoff Times):

• Alameda County: 336 customers (1 a.m. – 4 a.m.)
• Contra Costa County: 201 customers (1 a.m. – 2 a.m.)
• Napa County: 3,296 customers (4 a.m. – 6 a.m.)
• Santa Clara County: 236 customers (3 a.m. – 4 a.m.)
• Sonoma County: 135 customers (4 a.m – 6 a.m.)

PG&E said several Community Resource Centers will be open near areas impacted by the shutoffs, providing restrooms, hand washing stations, medical device charging and snacks.

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Power is expected to be restored on Friday.