About 20,000 people have fled from Napa, Sonoma and Yuba counties after three fires broke out across the area renowned for its vineyards.
At least one person has died as the fires spread rapidly, according to local media.
The governor of California declared an emergency as fire-fighters battled to control the wild blazes.
"These fires have destroyed structures and continue to threaten thousands of homes, necessitating the evacuation of thousands of residents," the declaration said.
