(CNN) - Some California communities will be without power Saturday, as PG&E takes precautions in areas at high fire risk.
The shutoff is set to start early Saturday morning and continue at least through Saturday afternoon, PG&E said Friday evening.
It will affect about 1,600 customers in Napa, Solano and Yolo counties, the utility company said.
The California Public Utilities Commission last week gave utilities new rules about intentionally cutting power to prevent wildfires. That followed the state's deadliest and most destructive wildfire, the Camp Fire.
"The safety of our customers and the communities we serve is our most important responsibility. We know how much our customers rely on electric service, and our decision tonight to turn off power is to protect our communities experiencing extreme fire danger," said Michael Lewis, PG&E's senior vice president of electric operations.
"Peak fire risk" in the Sierra foothills begins around 9 p.m. Saturday and lasts through noon Sunday, PG&E said.
The utility may also shut off power to about 30,000 customers in Butte, Yuba, Nevada, El Dorado and Placer counties, it said.
Customers can consult PG&E's interactive service map for updates.
Nearly 5 million people are under red flag warnings through Sunday afternoon across the Sacramento Valley, CNN meteorologist Haley Brink said.
Low humidity and strong winds, with gusts as strong as 50 mph, make for a critical fire threat, she said.
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