LOS ANGELES– California was buffeted by strong winds that caused humidity levels to plummet on Wednesday, prompting forecasters to warn of the potential for “extreme and life-threatening” wildfires.

Los Angeles County Fire Department crews scrambled to contain a small blaze fueled by erratic winds pushing flames through dry brush near Broad Beach along the Pacific Coast Highway in Malibu. The famous road lined with seaside mansions was closed as planes dropped water on the 40-acre (16-hectare) Large Fire area. Residents were urged to shelter in place and fire officials said two structures were on fire.

The National Weather Service office in Los Angeles replaced a red flag warning of increased fire danger with a rare “especially hazardous situation” label.

With winds predicted between 50 mph and 160 mph and humidity levels as low as 8%, parts of Southern California could experience conditions ripe for “extreme and life-threatening” fire behavior by Thursday, the weather service said.

Officials in several counties urged residents to be alert for rapidly spreading fires, power outages and downed trees during the last stretch of Santa Ana winds.

“Residents living in canyons, mountains and foothills should be ready to evacuate as soon as possible,” the LA County Emergency Management Office said in X. Some canyon roads were closed as a precaution and fire departments deployed resources to areas prone to fires.

Northwest of Los Angeles, the fast-moving Mountain Fire has prompted evacuation orders for several communities in an agricultural area near Santa Paula in southern Ventura County.

County fire spokesman Andrew Dowd said details were not available on how many people were under evacuation orders or how many structures were damaged.

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“There are many houses affected by the fire,” he said. “This is a rapidly moving fire.”

The last update on the size of the fire was around 9:15 a.m. at 248 acres, but Dowd said the fire has grown significantly since then.

Fire officials in southern Orange County said ash and debris were rising from the Airport Fire that ravaged the area earlier this year due to high winds, but no active fires were reported there Wednesday. Winds wreaked havoc on coastal cities, knocking down tree branches and overturning large garbage bins.

Forecasters also issued red flag warnings through Thursday from California’s central coast to the San Francisco Bay Area and counties to the north.

Winds of up to 30 mph are expected in many areas, with possible gusts reaching 55 mph at mountaintops, according to the weather service office in San Francisco.

Pacific Gas & Electric Co. said it had preemptively shut off power to a small number of customers late Tuesday in areas where strong winds could damage electrical equipment and spark fires.

More than 20,000 customers were without power in 17 Northern California counties Wednesday morning after Pacific Gas & Cuts off power to prevent equipment from starting a fire in dry and windy conditions.

Southern California Edison also preemptively shut off power to more than 46,000 customers on Wednesday, including more than 12,000 in Los Angeles County. The company’s website stated that more than 200,000 customers were expected to have their electricity cut off due to the risk.