Fire officials in the US State of California have reported further progress against the most lethal outbreak of wildfires in state history, as the death toll rose to 35.

The wind-driven blazes, which erupted on Sunday night in the heart of California’s renowned wine country, north of San Francisco, have destroyed an estimated 5,700 homes and businesses and forced the evacuation of at least 25,000 people.

The 35 confirmed fatalities – 19 in Sonoma County – mark the greatest loss of life from a single fire event on record in California, surpassing the 29 deaths from the Griffith Park fire of 1933 in Los Angeles.

With more than 200 people still missing on Friday in Sonoma alone, and rubble from thousands of incinerated dwellings yet to be searched, authorities have said the number fatalities from the so-called North Bay fires would likely climb higher.

Even as firefighters gained more ground during a second day of better weather, they braced for a return of higher temperatures, lower humidity and strong, gusty winds that could increase the threat to communities still in harm’s way.

Ground crews raced to clear drought-parched vegetation along the southern flanks of fires, removing highly combustible fuels adjacent to populated areas before extreme heat and winds were forecast to revive over the weekend.

“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 (Cal Fire), told a news conference.

As of Friday afternoon, 17 major wildfires – some encompassing several smaller blazes merged together – had consumed nearly 222,000 acres of dry brush, grasslands and trees across eight counties.

Officials have said power lines toppled by gale-force winds the first night may have sparked the conflagration, though the official cause remained under investigation.

Much of the devastation centered in and around the Sonoma County town of Santa Rosa, where whole neighborhoods were reduced to landscapes of gray ash, smoldering debris and burned-out vehicles.

Some victims were asleep when flames engulfed their homes, and many survivors had only minutes to flee.

Sonoma County Sheriff Robert Giordano said his office had investigated nearly 1,500 missing-persons reports stemming from the fires, and all but 235 had since turned up safe as of Friday evening.