Castaic, California - Firefighters who battled through the night to tame a new blaze that erupted near Los Angeles appeared to be making progress on Thursday, even as dangerous fire weather continued throughout Southern California.

A massive response involving aircraft, bulldozers, and 4,000 personnel had swung into action as flames raced across hillsides in Castaic, 35 miles north of Los Angeles.

Around 31,000 people were ordered to flee their homes, heaping misery on a region already reeling from the two deadly fires that ripped through America's second-biggest city this month.

The newly emerged Hughes Fire continued to grow overnight and, by Thursday, had consumed 10,000 acres, but its rate of growth had slowed considerably after an explosive first few hours.

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Firefighters said the blaze was 14% contained – an expression of how much of the perimeter they are confident is static.

Bryan Lewis of the National Weather Service warned the strong winds that had fanned the flames would continue Thursday, gusting up to 50 miles an hour at times.

But, he told AFP, there was good news in the forecast.

"We're expecting those winds to drop off.... Then by tomorrow, like late morning, afternoon, the wind should be a lot better.

"However, super, super dry conditions persist, with mostly single-digit relative humidities across most of the area," he said, describing conditions as "still dangerous."

Some much-needed rain over the weekend looked set to bring real relief to a region that has seen no significant precipitation for eight months, with up to half an inch forecast for much of Los Angeles.

"It's going to help in the near term. But, to really get us out of this fire season, we're going to need at least a couple more inches," Lewis said.

Over the burn scars left by the horrific Palisades and Eaton Fire, which together consumed 40,000 acres and killed more than two dozen people, officials were readying for possible mudslides and debris flows in the downpour.

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Workers in Los Angeles County have prepared sandbags, gravel, and concrete barriers that can be deployed if the rain gets heavy.

California Governor Gavin Newsom said he had prepositioned hundreds of personnel to try to head off problems caused by rain, including collapsing hillsides and poisonous chemicals being washed out of razed homes.

"Without vegetation to anchor the soil, heavy rainfall can lead to sudden and fast-moving debris flows, which can destroy homes, block roads, and pose serious risks to life and property," his office said.

"The state also works closely with its partners to prevent toxic runoff from entering waterways by installing physical filtration barriers."

President Donald Trump, who continues to claim falsely that California could solve its water problems by simply turning a spigot, is expected in the region on Friday.

Officials say he will meet firefighters and people who have been affected by the blazes.