SAN FRANCISCO (BLOOMBERG) - Violent winds are rattling Northern California, sending the risk of wildfires soaring and prompting the state's largest utility to cut power to prevent live wires from toppling into dry brush and sparking blazes.

Utility company Pacific Gas and Electric Company (PG&E) has cut electricity to 225,000 homes and businesses in areas north of San Francisco earlier on Sunday (Oct 25) and will turn off power to an additional 136,000 in areas including the East Bay and South Bay in the evening, impacting an estimated 1.1 million people as gusts exceeding 80kph swept through an area already bone-dry from heat and drought. Utilities in Southern California warned they may need to cut power, too.

"This is the strongest event we have seen so far this year," said Karleisa Rogacheski, a meteorologist with the National Weather Service in Sacramento. It's some of most dangerous weather the state has seen since the Camp Fire erupted in 2018, killing 85 people, she said.

PG&E said it may restore power starting Monday afternoon, though some customers may be left in the dark through Tuesday.

By mid-afternoon Sunday, at least three blazes had broken out north of Sacramento, according to the California Department of Forestry and Fire Protection.

The brutal winds, fires and blackouts are the latest blow for a state that's been battered by violent weather and has already seen a record 1.66 million ha scorched this year. PG&E has previously cut power four times in 2020 to prevent falling wires from igniting blazes in a region that's tinder dry from heat and drought. This round is the biggest yet as an estimated 4.2 million people are at risk from extreme fire conditions, according to the National Weather Service.

The winds, fuelled by a low pressure system in the Pacific Northwest, were gusting as high as 83kph in Northern California at 10.30am local time. Gusts in canyons and atop ridges could hit 112kph, just shy of hurricane strength.

Fire fighters were battling three new blazes in Shasta County, including the Point Fire which had burned 111ha and was 70 per cent contained by about 6pm local time, Cal Fire said. The nearby Dersch Fire had burned at least 20ha.

Come Monday, humidity will be as low as 6 per cent in Redding and just 5 per cent in Grass Valley, according to the National Weather Service. It comes as the state is already riddled with dry brush and grasses due to some of the warmest temperatures record over the last nine months, according to the US National Centres for Environmental Information.

PG&E is cutting power in stages. It began at 10am local time Sunday in the Northern Sierra region and will continue through Monday evening, the company said. The outages will hit 36 counties that include the San Francisco Bay area, the Sierra Nevada foothills, the Central Valley and the Central Coast.

The blackouts may hit densely populated parts of the San Francisco metropolitan area, including portions of Oakland, Berkeley and Marin County - cutting power to many residents as they are working from home due to the coronavirus pandemic. The city of Berkeley advised residents living in the hills to evacuate due to the fire risk, according to a statement.

In Southern California, Edison International said about 75,000 customers could lose power beginning Monday. That's about 225,000 people based on the size of the average California household. Sempra Energy's San Diego Gas & Electric Company is considering about 21,000 outages.

And Pacific Power, owned by Warren Buffett's Berkshire Hathaway, said it could switch off power in Northern California and Southern Oregon on Sunday due to the gusts, according to a statement.

Much of the US West is at risk from wildfires as dry weather and stiff winds turn hillsides, forests and scrub land into tinderboxes. In Colorado, two of the largest fires in state history have forced the closure of Rocky Mountain National Park and triggered the evacuation of nearby towns.

More than 8 million people across California will be in high-risk zones, including the cities of Sacramento, Stockton, and San Bernardino, the US Storm Prediction Centre said in its long-range forecast.

The outages come on the heels of a blistering heat wave that gripped California earlier this month, driving temperatures to record daily highs. In August, a freak lightning storm sparked more than 150 wildfires in 24 hours. Days before that, the state's grid operator ordered the first rotating outages since the Enron-era energy crisis of 2001 as scorching weather sent electricity demand surging.

PG&E began resorting to preventative shutoffs after its equipment caused some of California's worst blazes, forcing the company into bankruptcy last year. PG&E emerged from Chapter 11 in July after paying US$25.5 billion (S$34.6 billion) to resolve fire claims.