SAN FRANCISCO — About 90,000 residents were ordered to evacuate towns near a massive Northern California wildfire Saturday, and the state’s largest utility began power shut-offs for an estimated 2.35 million people due to forecasts of severe winds and extreme fire danger.
Two previous blackouts in recent weeks were carried out amid concern that gusty winds could disrupt or knock down power lines and spark devastating wildfires.
The new evacuation order encompasses a huge swath of wine country stretching from the inland community of Healdsburg west through the Russian River Valley and to Bodega Bay on the coast, Sonoma County Sheriff Mark Essick said. An even broader area is under a warning for residents to get ready to leave at a moment’s notice.
Some gusts this weekend might reach 75 miles per hour or higher as part of a ‘‘historic’’ wind event, the National Weather Service said. The winds could lead to ‘‘erratic fire behavior’’ and send embers miles ahead of the main blaze, warned the California Department of Forestry and Fire Protection.
Pacific Gas & Electric said a new wave of blackouts started Saturday evening, affecting about 940,000 homes and businesses in 36 counties for 48 hours or longer. The city of San Francisco was not in line for a blackout; shut-offs were ordered for most of the rest of the San Francisco Bay Area, the wine country to the north and the Sierra foothills.
At an evening briefing, the sheriff pleaded with residents in the evacuation zone to get out immediately, citing the 24 lives lost when a wildfire swept through the region two years ago.
‘‘I'm seeing people reporting that they’re going to stay and fight this fire,’’ Essick said at an evening briefing. ‘‘You cannot fight this. Please evacuate.’’
The wind event will peak early Sunday and is likely to be the strongest in several years, said PG&E meteorologist Scott Strenfel.
‘‘It’s likely that many trees will fall, branches will break,’’ raising the risk of damage to utility infrastructure, Strenfesl said at a Saturday evening briefing. Relative humidity will dip into single digits, he said.
PG&E’s shut-off order came as firefighters battled fires in Northern and Southern California.
A wildfire Thursday destroyed 18 structures in the Santa Clarita area north of Los Angeles and led to evacuation orders for up to 50,000 residents, although nearly all were allowed back home after Santa Ana winds began to ease.
Marcos Briano returned to find his property intact, while homes down the street were destroyed.
‘‘I'm thankful that nothing happened to my house, but I feel bad for my neighbors,’’ Briano, 71, said Saturday.
Sheriff’s officials said human remains were found within the wide burn area, but it’s too soon to know if the death is connected to the blaze. The Tick fire was 55% contained.
To the north, firefighters raced to make progress against a blaze near Geyserville in Sonoma County before ferocious ‘‘diablo winds’’ returned. The Kincade fire had burned 77 buildings, including 31 homes, and swept through more than 40 square miles of the wine-growing region. It was just 10% contained by Saturday evening.
A firefighter and two civilians were injured when they were overwhelmed by flames as they tried to evacuate from approaching flames, authorities said.
‘‘The firefighter was forced to deploy his fire shelter, where he shielded them from fire,’’ Cal Fire said in a statement. After the flames passed, all three were hospitalized with non-life-threatening injuries, the statement said.
Several thousand people living in small communities in neighboring Lake County were warned to be ready to evacuate if an order is given. The area was the scene of a 2015 wildfire that killed four people and burned nearly 2,000 homes and other buildings.
No cause has been determined for any of the current fires, but PG&E said a 230,000-volt transmission line near Geyserville had malfunctioned minutes before that fire erupted Wednesday night.
The utility acknowledged that the discovery of the tower malfunction had prompted a change in its strategy.
‘‘We have revisited and adjusted some of our standards and protocols in determining when we will de-energize high-voltage transmission lines,’’ Andrew Vesey, CEO of Pacific Gas & Electric Co., said at a briefing Friday.
The weekend forecasts detail what could be the strongest winds of the year coupled with bone-dry humidity. Many homes and business facing power shut-offs were far from current fires. PG&E cast the blackouts as a matter of public safety, aimed at preventing the kind of blazes that have killed scores of people over the past couple of years, destroyed thousands of homes, and ran up tens of billions of dollars in claims that drove the company into bankruptcy.
‘‘Any spark, from any source, can lead to catastrophic results,’’ Vesey said. ‘‘We do not want to become one of those sources.’’
The possible link between the wine country fire and a PG&E transmission line contained grim parallels to a catastrophic fire last year that tore through the town of Paradise, killing 85 people and destroying thousands of homes in the deadliest U.S. fire in a century.
State officials concluded that fire was sparked by a PG&E transmission line.
Many residents in the blackout-targeted region had barely recovered from a previous shut-off.
Jon Robinson, 52, of Rough and Ready, said the earlier shut-off put him in the hospital for several days for the stomach flu. He'd been tending to his sick grandson and got worn down between that and taking care of animals on his ranch.
Robinson was unsure if his family, who moved to California seven years ago, will remain in the state much longer.
‘‘Before this, we planned on staying,’’ he said. ‘‘But I'll tell you what, it’s just too nerve-racking.’’
For many people affected by the shut-offs, there have been painful business-related losses.
In Newcastle, about 30 miles northeast of Sacramento, 65-year-old Sukhwinder Singh works the cash register at Quality Market, a local convenience store. During the previous outage, Singh said he worked in the dark, but customers did not want to buy his warm soda and melted ice cream. He estimates he lost about $1,100 in sales and products. Singh has a generator now but said he can’t keep it running all night when the store is closed.
‘‘I don’t know how we can pay the bills at the end of the month,’’ he said.
In Loomis, about 5 miles from of Newcastle, Scott Paris estimates that he lost about $20,000 in business proceeds when he had to shut down his High-Hand Nursery and Cafe when PG&E turned off the power earlier this month. And that was just for about 24 hours during a weekday.
This time he expects to lose power on a weekend, when he might typically do $50,000 to $60,000 worth of business on a beautiful fall Sunday.
‘‘We’re scrambling to get enough generators,’’ he said. ‘‘If this is the new normal, it’s going to drive up a lot of costs. It drives up stress.’’
In Marin County, just north of San Francisco, the sheriff’s office warned that a power shut-off would likely knock out some traffic lights. Intersections with inoperable lights should be treated as a four-way stop, the office said.
Even before the new blackout order, the University of California, Berkeley announced it was canceling all Saturday afternoon classes, as well as other indoor events and activities scheduled through Sunday.
A Florida utility, Florida Power & Light, announced it was sending 100 line workers and support staff to help PG&E restore power to areas with outages caused by the wildfires.