Even as crews made enough progress for authorities to begin contemplating re-population of some evacuated areas, they were bracing for another onslaught of hot, dry winds that could fan the fires.
"We are diligently working hard. We’ve challenged the troops to get out there and secure mainly the south parts of these fires in preparation for those strong north winds,” Bret Gouvea, deputy chief of the California Department of Forestry and Fire Protection, said at an afternoon news conference.
He said contingency plans were being made for other communities in case the fires spread.
The Napa Valley town of Calistoga faced one of the biggest threats. Its 5000-plus residents, ordered to leave their homes on Wednesday night, remained evacuated.
As of Friday afternoon several of the 17 major wildfires burning across Northern California had merged into massive, largely out-of-control conflagrations, having burned a combined 89,740 hectares (221,754 acres) of dry brush and grasslands.
The 32 confirmed fatalities mark the greatest loss of life from a single fire event on record in California, three more than the 29 killed by the Griffith Park fire of 1933 in Los Angeles.
At least 18 people died in the so-called Tubbs Fire in Sonoma County, which now ranks as the deadliest single fire in the state since 1991. Officials said the death toll would likely rise as burned homes and businesses were searched.
Many of the more than 1000 people initially added to a list of those unaccounted for had been found, Sonoma County Sheriff Robert Giordano said at the news conference, but 256 were still missing.
Giordano said 45 search-and-rescue teams and 18 detectives had been deployed to comb ruined neighborhoods for more victims.
'CRITICAL FIRE WEATHER CONDITIONS'
Winds of up to 100km/h and humidity of just 10% will create "critical fire weather conditions" and "contribute to extreme fire behavior" on Friday afternoon and into Saturday, the National Weather Service said.
A force of 8000 firefighters was working to reinforce and extend buffer lines across the region where the flames have scorched more than 77,000ha, an area nearly the size of New York City.
Yasmin Gonzalez, 28, her four children and husband, a grape picker, were anxious to leave the shelter and return to their apartment in Sonoma.
"It's horrible to leave your home, and your things and not know what's going to happen," Gonzalez said on Friday.
The region’s health system has also been weakened by the fires, with Kaiser Permanente forced to close its Santa Rosa medical center and pharmacy, and many doctors and small practices evacuated.
Kaiser said on Friday that it was rerouting patients, some of whom complained of respiratory ailments as a result of smoke, to nearby medical centers.
The cause of the blazes was under investigation, but officials said Pacific Gas and Electric Company power lines toppled by gale-force winds on Sunday may be to blame.
The California Public Utilities Commission has directed PG&E to preserve all evidence including "all failed poles, conductors and associated equipment from each fire event" in Napa, Sonoma and Solano counties.
The year's wildfire season is one of the worst in history in the United States, with nearly 3.5 million hectares burned so far, just behind 2012, according to the National Interagency Fire Center. In the worst year, 2015, about 3.7 million hectares burned.
The fires struck the heart of California's world-renowned wine-producing region, wreaking havoc on its tourist industry and damaging or destroying at least 13 Napa Valley wineries.
The state's newly legalised marijuana industry was also hit hard, with at least 20 pot farms in Sonoma, Mendocino and Napa counties ravaged, a growers' association said.
