Firefighters are racing to contain the frontiers of two Los Angeles wildfires burning for the sixth straight day, taking advantage of a brief respite in hazardous conditions before high winds are expected to fan the flames anew.
At least 24 people have died in what California Governor Gavin Newsom said could be the most devastating natural disaster in US history - one that has destroyed thousands of homes and forced 100,000 people to evacuate.
Flames have reduced whole neighbourhoods to smouldering ruins, levelling homes and leaving an apocalyptic landscape.
Officials said at least 12,300 structures have been damaged or destroyed.
"LA County had another night of unimaginable terror and heartbreak," Los Angeles County Supervisor Lindsey Horvath said.
Aerial firefighters, some of them scooping water out of the Pacific Ocean, dropped water and retardant as land crews with hand tools and hoses held the line of the Palisades Fire as it encroached on the upscale Brentwood section and other populated areas of Los Angeles.
That fire on the western side of town has consumed 96sq km and was 13 per cent contained, a figure representing the percentage of the fire's perimeter that firefighters have under control.
The Eaton Fire in the foothills east of Los Angeles scorched another 57sq km - almost the size of Manhattan - and firefighters increased the containment to 27 per cent, up from 15 per cent a day earlier.
North of the city, the Hurst Fire was 89 per cent contained, and three other fires that had ravaged other parts of the county were now 100 per cent contained, the California Department of Forestry and Fire Protection (Cal Fire) reported, although areas within the containment lines could still be burning.
Firefighters got a temporary break from the weather at the weekend as Santa Ana winds, which reached hurricane force earlier in the week, finally eased.
The dry winds originating from the inland deserts fanned flames and blew embers up to 3km ahead of the front lines.
But, in an area that has not received any rain of note since April, the National Weather Service forecast Santa Ana winds of up to 80 to 112km/h would resume on Sunday night (US West Coast time) and last through to Wednesday.
Officials warned the entire Los Angeles County population of almost 10 million that anyone could be ordered to evacuate from the flames and toxic smoke.
By Sunday, more than 100,000 people in Los Angeles County had been ordered to evacuate - down from a previous high of more than 150,000 - while another 87,000 faced evacuation warnings.
"These winds combined with low relative humidities and low fuel moistures will keep the fire threat in all of Los Angeles County very high," Los Angeles County Fire Chief Anthony Marrone told reporters.
He said evacuated areas might not be reopened until red flag conditions lifted on Thursday.
The Los Angeles County Medical Examiner reported 24 deaths from the fires.
Private forecaster AccuWeather has estimated the damage and economic loss at $US135 billion ($A220 billion) to $US150 billion ($A244 billion).
Newsom signed an executive order on Sunday temporarily suspending environmental regulations for destroyed homes and businesses to help expedite the monumental rebuilding effort.
Active duty military personnel are ready to support the firefighting effort, FEMA Administrator Deanne Criswell said on Sunday, adding the agency had urged residents to begin filing for disaster relief.
Firefighters from seven states, Canada and Mexico have already converged on the Los Angeles area to help fire departments from around the state.
In Altadena on the edge of the Eaton Fire, Tristin Perez said he never left his home, defying police orders to evacuate as the fire raced down the hillside.
Instead, Perez insisted on trying to save his property and his neighbours' homes.
"Your front yard is on fire, palm trees lit up - it looked like something out of a movie," Perez told Reuters in an interview in his driveway.
"I did everything I could to stop the line and save my house, help save their houses."
His one-storey yellow duplex survived. So did two more homes next door. Across the street, entire houses burned to the ground.
"A lot of these areas still look like they were hit by a bomb," Los Angeles County Sheriff Robert Luna said.
"There are live electrical wires, gas lines and other hazards."
