Close to 1000 still missing in US fires

California's Camp Fire has claimed 77 lives and destroyed more than 13,600 homes as authorities continue to sift through charred ruins for more human remains.

Remains of five more people have been found in California, bringing the wildfire death toll to 76. (AAP)

Emergency services are sifting through the charred wreckage of California's deadliest ever wildfire, searching for signs of nearly 1000 people believed still missing as crews made progress in bringing the blaze under control.

The remains of 77 people have been recovered, the Butte County Sheriff's Office said late on Sunday, as it cut the number of missing to 993 from 1276. It gave no other details.

The Camp Fire broke out in Northern California on November 8 and last week all but obliterated Paradise, a mountain town of nearly 27,000 people around 150 km north of state capital Sacramento.

Officials said it had consumed about 610,000 hectares and was 65 per cent contained late on Sunday, up from 60 per cent earlier in the day, as prospects of a heavy rainstorm from late Tuesday onwards raised hopes that that percentage will rise as the week progresses.

They said full containment was not expected until Nov. 30, however.

Up to 10cm of rain is forecast to fall north of San Francisco between late Tuesday and Friday.

The rain would also make it harder for forensic teams sifting through ash and dirt looking for the bones of the dead.

Pathologists from the University of Nevada, Reno, worked through the weekend as firefighters peeled back debris, collecting bits of burned bones and photographing everything that might help identify the victims.

The storm, which is expected to carry moderate winds of 25-32km/h could also cause problems for evacuees, hundreds of whom are sheltering in tens and cars.

It isn't clear how many people are in need of shelter but as many as 52,000 people had been ordered to evacuate

"While it isn't an exceptionally strong storm, the recent burns make mud slides on hills and slopes a real danger," Burke said.

South of Sacramento near Malibu, at least 5cm of rain are expected to fall on a second fire, the Woolsey. Known to have killed three people, it was 88 per cent contained on Sunday and full containment was expected on Thanksgiving Thursday.

The cause of both fires is under investigation, but electric utilities reported localised equipment problems around the time they broke out.