Erratic wind and heat gripping a swath of California from San Jose to the Oregon border drove the flames, which were north of the wine country region where wildfires killed 44 people and destroyed thousands of homes and businesses last October.
Farther north, a fire spanning about 1km in Tehama County destroyed "multiple residential and commercial buildings", Cal Fire said. But firefighters appeared to be making good progress - the Stoll Fire was halfway contained and some evacuees were allowed to return home, authorities said.
A second fire in Tehama County consumed 14sq km, but no buildings were reported burned. The so-called Lane Fire threatened 200 structures and some homes had been evacuated, Cox said. It was 10 per cent contained.
A fire in neighbouring Shasta County grew to more than 4sq km and was 20 per cent contained. The so-called Creek Fire had damaged no structures but did prompt evacuations.
The cause of each blaze was under investigation yesterday. No one was reported hurt.
More than 230 firefighters using helicopters, bulldozers and other equipment were battling the Pawnee Fire in a rugged area that made it difficult to tackle.
- AP