Fast-moving Santa Ana winds are expected to blast through Southern California on Wednesday, whipping up new wildfires after a brief respite for firefighters a day earlier.

The U.S. National Weather Service (NWS) issued a rare “extreme red flag” warning for wildfires.

“I don’t know if I’ve ever seen us use this warning,” said NWS forecaster Marc Chenard. “It’s pretty bad.”

The Santa Ana winds blowing westward off the desert and mountains into Los Angeles and Orange County are expected to reach sustained speeds of about 80 to 110 km/h Wednesday and into Thursday, Chenard said.

Firefighters got ready to do battle again after a day of light breezes that helped them gain ground against a blaze displacing thousands of Los Angeles residents near the Getty Center museum. Strike teams and equipment were posted on standby at strategic points throughout the state.

City arson investigators said on Tuesday the Getty fire was likely to have been caused by a broken tree branch being blown into power lines during high winds on Monday morning.

Major power cuts 

Electricity remained cut off to roughly half a million homes and businesses in Northern and Central California on Tuesday as a precaution by the state’s largest utility.

Gov. Gavin Newsom, who has accused utilities of failing to adequately modernize and safely maintain their power systems, paid a visit to the Getty fire zone on Tuesday afternoon.

“This is a challenging time,” Newsom told reporters at a command centre in the University of California’s Los Angeles campus.

Fire officials are worried that strong winds will whip up embers like these in Calistoga, Calif. (Noah Berger/The Associated Press)

At the start of the day, firefighters in Los Angeles and those battling a much larger conflagration in Northern California’s Sonoma County wine country took advantage of lighter winds to make headway before hazardous winds reemerged.

Fire officials worried that high winds forecast to gust to 113 km/h or more would lift embers from smoldering hot spots and carry them into unburned vegetation, re-igniting and spreading flames anew.

Citing progress made against the Kincade Fire, Newsom said the number of evacuees in Northern California had diminished from 190,000 at the peak of that blaze to 130,000 on Tuesday.

Property losses from the Kincade, listed at 15 per cent contained, were put at 189 homes and other structures, double Monday’s tally.

Gains in fight against Getty fire

An army of some 1,100 firefighters battled the Getty fire Tuesday in a narrow window of slower winds and consolidated those gains a day after flames and embers spread over scrub-covered slopes around expensive homes on the city’s west side.

By early Wednesday, crews had managed to confine the blaze to about 263 hectares while carving solid containment lines around 15 per cent of its perimeter.

Crews have made some progress in their fight to contain the Getty Fire, seen here on Monday. The fire is burning along the 405 freeway north of Los Angeles. (Gene Blevins/Reuters)

In Northern California, where firefighters struggled for a sixth day against a sprawling blaze in Sonoma County’s wine-making region, high-wind forecasts prompted Pacific Gas and Electric Co to impose a new round of blackouts for nearly 600,000 homes and businesses.

That included about 400,000 customers blacked out in a power shut-off that PG&E instituted days earlier, the company said.

Early Wednesday, PG&E announced that it had restored about 73 per cent of the 970,000 or so customers affected in earlier shutoffs.

Utilities serving Southern California’s more highly urbanized areas have imposed smaller-scale outages.

The size of the Getty fire’s evacuation zone was reduced by roughly 3,000 homes on Tuesday but residents of about 7,000 dwellings remained displaced, fire officials said. At least a dozen homes have been destroyed so far.