The Clover Fire near the rural community of Happy Valley began around 1 p.m. Monday and quickly spread through grass and oak, state fire spokeswoman Teresa Rea said. Happy Valley is about 150 miles north of Sacramento.
The fire was fueled by strong winds and dry conditions.
"It was the perfect storm," Rea said.
Multiple outbuildings and vehicles also were damaged. Mandatory evacuations are in place for some homes, though Rea did not know how many.
Fire crews did, however, make good progress against the blaze overnight, raising containment from 5 percent to 40 percent, she said.
More than 1,100 firefighters are battling the blaze. The cause is under investigation.
Meanwhile, a fire burning in a San Francisco Bay Area wilderness park appeared to be under control. Crews made considerable progress overnight against the fire in Mount Diablo State Park in Contra Costa County, more than doubling containment and reducing the number of threatened homes.
The fire was 45 percent contained as of Tuesday morning, up from 20 percent the previous night, officials said. It has burned a little over 5 square miles.
That number was lowered from the previous day because of better mapping.
State fire spokesman Steve Kaufmann said 75 homes are now threatened, down from 100 homes.
He said the fire isn't showing much active behavior.
