Authorities hope weaker winds will help more than 10,000 firefighters battle the deadliest blazes in California history, which have killed at least 40 people and destroyed thousands of structures.
Fast-moving fires spread by shifting winds forced thousands more to evacuate their homes on Saturday as the death toll over the week rose to 40, with hundreds missing.
More than 10,000 firefighters supported by air tankers and helicopters battled 16 major wildfires in areas north of San Francisco that have consumed nearly 86,000 hectares, or roughly 865 sq km - an area larger than New York City.
The 40 confirmed fatalities, including 22 in Sonoma County, make it California's deadliest-ever fire event, surpassing the 29 deaths from the Griffith Park fire of 1933 in Los Angeles.
With 235 people still missing on Saturday in Sonoma County alone and rubble from thousands of incinerated dwellings yet to be searched, authorities expect the death toll to climb.
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Some 100,000 people have been forced from their homes, including 3,000 on Saturday from the city of Santa Rosa, about 80 km north of San Francisco. The fires have damaged or destroyed about 5,700 structures, reducing homes and businesses to ash.
Some victims were asleep when flames engulfed their homes, while others had only minutes to flee.
"This is truly one of the greatest tragedies that California has ever faced. The devastation is just unbelievable. It is a horror that no one could have imagined," California Governor Jerry Brown said on a visit to a devastated city.
