Some 15,000 people evacuated a resort town in the mountains northeast of Los Angeles the only major community still threatened after a week of fires that have killed 20 people, destroyed more than 2,800 homes and burned nearly 750,000 acres.
"Mother Nature is finally starting to help us here," Andrea Tuttle, director of the California Department of Forestry, told NBC's "Today" show. "We're hoping that within the week the hot flames will be died down."
Seven fires burned across four counties as patches of heavy fog moved into the mountains overnight. Friday's high was expected to be a chilly 44 at Big Bear Lake, with a chance of snow by nightfall, but winds could still gust to 31 mph.
Firefighting efforts were both aided and hindered by the fog, which brings needed moisture but also extremely low visibility, prompting worries of injury in thick forests or on dark roads.
"It's a two-edged sword," fire information officer Candace Vialpando said. "You're moving at a slower pace just to see the ground."
Meanwhile in San Diego County, moist air helped firefighters battling the Cedar Fire near Julian, a popular weekend getaway spot.
The fire the largest individual blaze in California history at more than 270,000 acres, according to state officials "is finally showing some sign of winding down," San Diego County Sheriff Bill Kolender said.
Authorities hoped they could begin allowing the thousands of evacuated residents to return to check on their homes.
On Thursday, tumbleweeds and trash bags tossed across empty roads. Firefighters dug in and cut lines the width of 10 bulldozers through the forest in an effort to head off flames that had burned some 350 homes in Cedar Glen near Lake Arrowhead.
Officials worried that the blaze which at times moved a quarter-mile a minute, by one firefighter's account could sweep over the ridge and engulf the lakeside community of Fawnskin and the rest of the Big Bear Valley.
The blaze advanced onto the campus of a private school in nearby Running Springs overnight, but firefighters protected the building.
"We are cautiously optimistic that we can get a handle on this fire," said Los Angeles County Fire Capt Mike Carnes.