The Rocky Fire exploded overnight, burning 47,000 acres as of Sunday morning and threatening 6,000 structures in Lake, Yolo and Colusa counties.
The fire has destroyed 24 residences, according to the U.S. Forest Service, and is the biggest of numerous fires burning in drought-plagued Northern California.
"Dry thunderstorms" — lightning and wind with very little rain — are the main cause of roughly two dozen large blazes that have led to one firefighter's death and prompted Gov. Jerry Brown to declare a state of emergency.
The storms are expected to continue through the weekend, forcing nearly 9,000 firefighters engaged in the battle to keep an eye on the sky as they confront the burning ground around them.