Rain in the forecast could aid crews fighting California's deadly wildfires while raising the risk of flash floods and complicating efforts to recover remains of those killed.
Residents in communities charred by the Los Angeles-area fire stacked sandbags as they prepared for possible downpours that threatened to unleash runoff from hillsides left barren by flames.
In Northern California, teams continued sifting through ash and debris as they searched for bodies in and around the decimated town of Paradise.
"The task is arduous," said Rick Crawford with the California Department of Forestry and Fire Protection. "And the possibility exists that some people may never be found."
With the death toll at 81 in the state's most destructive wildfire, there are still nearly 870 people still unaccounted for.
Authorities trying to identify the scores of people killed are using rapid DNA testing that produces results in just two hours.
But the technology depends on people coming forward to give a DNA sample via a cheek swab, and so far, there are not nearly as many volunteers as authorities had hoped for.
The burned area surrounding Paradise, which is about 230km northwest of San Francisco, will see rain starting on Wednesday.
The precipitation could help knock out the flames, but it could also hinder the search by washing away fragmentary remains and turning ash into a thick paste.
The Camp Fire, which has burned an area about of about 620 square kilometerres, has destroyed around 13,000 homes, and has been 75 per cent contained.
In Southern California, people who worried days earlier that their homes might be consumed by flames were now taking action to guard against possible debris flows caused by the Pacific storm set to come ashore the day before Thanksgiving.
Residents filling sandbags at Malibu's famous Zuma Beach were mindful of the disaster that struck less than a year ago when a downpour on a fresh burn scar up the coast sent home-smashing debris flows through Montecito, killing 21 people and leaving two missing.
The 400-square-kilometre Woolsey Fire was almost entirely contained, with 1500 buildings destroyed and 341 damaged.
The major remaining closed area was centred in the rugged Santa Monica Mountains that rise high above the Malibu coast.
