LOS ANGELES — California's largest utility once again began shutting off electricity to nearly a half-million people on Wednesday to protect against wildfires sparked by their equipment.

And yet another widespread blackout could be needed next week, it said.

Hot, dry Santa Ana winds and low humidity were creating a high risk of damage and sparks and "rapid wildfire spread," Pacific Gas and Electric Corp., or PG&E, said in announcing that it was beginning to cut off power to 179,000 customers in the northern part of the state Wednesday afternoon.

The blackouts are to take effect in parts of 17 counties — including large communities like Santa Rosa, Sonoma and Napa but not San Francisco or San Jose — at least through Thursday afternoon and through Friday afternoon in other parts of the region.

PG&E said that's when the last of the dangerous conditions are expected to end, and only then can it go out to inspect the lines for damage.

In the southern part of the state, Southern California Edison said Wednesday afternoon it was monitoring more than 300,000 customers for a potential power shutoff that could begin Thursday. The potential coverage area includes large communities like San Bernardino, Malibu, Irvine, Glendale and Palm Springs but not Los Angeles itself, which is served by a separate power company.

A power "customer" can be a single residence or a large business; a standard conversion that many utilities use assesses 2½ people per customer, meaning as many as 450,000 people could be affected in Northern California. Southern California Edison's potential blackouts could affect more than 750,000 more.

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Mark Quinlan, PG&E's senior director for emergency preparedness and response, noted at a news conference Tuesday that the projected outage area in Northern California was smaller than the company had warned on Monday, when it said as many as 209,000 customers could be affected.

But "the forecast continues to show the potential for hot, dry, windy weather," he said, saying final decisions would likely come Wednesday morning.

It's the second massive blackout in the nation's most populous state in just two weeks, after PG&E shut off power to almost 2 million people in rolling blackouts beginning Oct. 9.

To make matters worse, Bill Johnson, PG&E's chief executive, said the company was monitoring another "weather event" that could trigger rolling blackouts over the weekend or next week.

"It's being worked on," he said.

The National Weather Service offered little hope for optimism, forecasting strong offshore winds over the weekend.

"Not only will this bring another fire weather threat, but potentially a more widespread wind issue," it said, predicting wind gusts exceeding 60 mph and "critical fire weather conditions" over the northern San Francisco Bay Area as early as Sunday.

The utility was widely criticized for the relative lack of notice it gave customers earlier this month, when heavy user volume crashed its website for long periods, keeping customers from blackout and safety updates.

The company set up a separate website to handle the crush of visitors this time — but it went down for about 45 minutes Tuesday morning, Johnson said. Customers were being directed back to the utility's main website, pge.com.

At Village True Value Hardware in Santa Rosa, in Sonoma County, manager Kim Scheffer was exasperated as she again directed customers to gas cans and batteries.

"I think it's not panic per se — just, 'eh, we've got to do this again?'" Scheffer told NBC affiliate KSEE of Fresno.

In a letter to PG&E on Tuesday, Gov. Gavin Newsom repeated that the company's need for fire-prevention blackouts and its performance during the earlier power shutoff were "unacceptable," blaming "decades of PG&E prioritizing profit over public service" for its failure to maintain and upgrade its equipment.

Newsom again demanded that PG&E reimburse customers for lost business, housing alternatives or spoiled food and medicines. Like other utilities, PG&E says it doesn't compensate customers for blackouts needed for safety reasons.

Johnson, the chief executive, appeared to soften somewhat on that position Tuesday.

With a significant shutoff "right in front of us, and we have a potential one right behind it, you can imagine we are focused on those things," Johnson said.

"Haven't had a lot of time to think about this. I'm thinking about it. I am considering his request," he said.

While Johnson said compensating customers would be "inconsistent with history here with the public policy," he said that "when we get done with fire season and we can quit just thinking in 24-hour increments, there's a time to have a policy discussion about the right answer."

"So we're not rejecting it, but we have more immediate things" to worry about, he said.

Because California's winter fire season runs from October to April, Johnson's timetable means discussions on compensation couldn't begin until well into next spring.

Johnson said agreeing to compensation could further complicate bankruptcy proceeding for PG&E, which faces huge liabilities from its role in several highly destructive fires that burned hundreds of thousands of acres of Northern California in 2017 and 2018.

More than 80 people were killed last year in one of the blazes, which was dubbed the Camp Fire. The company could be on the hook for up to $18 billion in financial damages at a scheduled trial over its responsibility in the Camp Fire and other devastating wildfires going back to 2017.