SAN FRANCISCO (AP) — Pacific Gas & Electric cut power Sunday to more than 100,000 California customers and planned outages for many more to prevent the chance of sparking wildfires because of extreme fire weather.

More than 1 million people could be affected by planned outages as California braces for a return of gusty winds and bone-dry weather that carry the threat of downing or fouling power lines or other equipment, which in recent years have been blamed for igniting massive and deadly blazes.

It’s the fifth time this year that PG&E, the nation's largest utility, has cut power to customers. Power was shut off Sunday for 117,000 customers in 18 Northern California counties and outages were expected to continue, affecting as many as 361,000 customers in all.

Further south, Southern California Edison said it was considering safety outages for 71,000 customers in six counties starting Monday, with San Bernardino County potentially the most affected.

Sheriff Kory Honea of Butte County said he's concerned about residents in foothill communities during these blackouts as cellular service can be spotty and it's the only way many can stay informed when the power is out.

“It is quite a strain on them to have to go through these over and over and over again,” he said.

The National Weather Service issued red flag warnings for much of the state, predicting winds of up to 35 mph (56 kph) in lower elevations and 80 mph (129 kph) in some mountainous areas of Southern California.

The concern is that any spark could be blown into flames sweeping through tinder-dry brush and forestland. The areas of greatest risk include the Sacramento Valley and mountainous areas of Southern California, the National Weather Service said.

The conditions could equal those during devastating fires in California’s wine country in 2017 and last year’s Kincade Fire, the National Weather Service said. Fire officials said PG&E transmission lines sparked that Sonoma County fire last October, which destroyed hundreds of homes and caused nearly 100,000 people to flee.

Southern California saw cooler temperatures and patchy drizzle during the weekend, but weather conditions were expected to change dramatically early Monday. Los Angeles County urged residents to sign up for emergency notifications and prepare to evacuate, preferably arranging to stay with family or friends in less risky areas who aren't suspected to have the coronavirus. Local fire officials boosted staffing as a precaution.

“The reality is come midnight and through Tuesday we're going to be in the most significant red flag conditions we've had this year,” said Kevin McGowan, director of the county’s Office of Emergency Management.

More than 8,600 wildfires have scorched well over 6,400 square miles (16,576 square kilometers) and destroyed about 9,200 buildings in California this year. There have been 31 deaths.

All of the huge fires have been fully or significantly contained. But more than 5,000 firefighters remain committed to 20 blazes, including a dozen major incidents, the California Department of Forestry and Fire Protection said.

Many of this year’s devastating fires were started by thousands of dry lightning strikes. But some of the fires remain under investigation for potential electrical causes.

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Associated Press writer Christopher Weber in Los Angeles contributed to this report.