Northern California wildfires flare a new
The death toll in the western US state climbed to 21 on Wednesday and was expected to rise higher still.
Officials said they had thousands of firefighters battling 22 blazes burning and more were coming from nearby states.
Ken Pimlott, chief of California Department of Forestry and Fire Protection, said close to 8,000 firefighters had been deployed and were fighting the blazes by air and on the ground.
Pimlott said Oregon, Nevada, Arizona and Washington are sending firefighters and the US Forest Service is sending fire engines, bulldozers and hand crews.
He also said there are concerns several fires could merge into one big blaze.
Winds of up to 80km per hour (kph) and 10 percent humidity were forecast for later on Wednesday and into Thursday for the region, fire officials said.
Among the deadliest
The fires north of San Francisco are among the deadliest in California's history.
The blazes have left at least 180 people injured and have destroyed more than 3,500 homes and businesses.
More than 4,400 people were staying in shelters as of Wednesday.
"The potential for new fires that could grow exponentially as these fires did in such a short time period is there," said Lynne Tolmachoff, spokesperson for California Department of Forestry and Fire Protection.
The weather had given firefighters a reprieve on Tuesday as cooler temperatures, lower winds and coastal fog let them make headway against the fires that had burned 115,000 acres.
New evacuation orders were posted overnight across Sonoma County, north of San Francisco.
About 155 people were missing in Sonoma County, although 45 others had been found and some of those unaccounted for may be due to confusion surrounding evacuations.
Economic impact
The city of Santa Rosa was particularly hard hit by the so-called Tubbs fire, which damaged a Hilton hotel and destroyed a mobile home park, among other damage.
At least 11 people have been killed by that fire alone, officials said.
It is the deadliest California wildfire since 2003, when the Cedar fire killed 15 people in San Diego, and the sixth deadliest since records began, according to state records.
Napa Valley Vintners, a trade group, said it was too early to assess the economic impact on Northern California's celebrated wine country.
At least four wineries suffered "total or very significant losses" and at least nine reported damage, the group said.
California Governor Jerry Brown declared a state of emergency in several northern counties, as well as in Orange county in Southern California, where a fire destroyed 15 structures and damaged 12, the Anaheim Fire and Rescue Department said.