Fire-fighters in Northern California are struggling to contain more than 1,000 wildfires that have been burning for more than a week.
The flames have burnt more than 500 sq miles (1,400 sq km) of land and are threatening the coastal town of Big Sur, California officials said.
President George W Bush declared a state of emergency for the entire state on Saturday and ordered federal aid.
Most of the fires were sparked by lightning in dry wilderness areas.
The lightning storms, on 21 June, were unusually intense, and the flames quickly spread through forests and scrubland that have been left parched by lower than average winter rainfall.
The US Forest Service said it expects a long fire season for Northern California, with more summer storms in the coming months.