Around 200 firefighters are tackling blazes raging through rugged terrain in Ventura County, California.
High temperatures and high winds are spreading the wildfires through the southern Californian county.
The Channel Islands campus of California State University has been evacuated due to a fire covering more than eight square kilometres.
The fires have destroyed at least one house and Ventura County officials are warning residents to be prepared to leave their homes.
Hardly any rain has fallen in California so far this year, making the state as dry as it would usually be in autumn, when wildfires are usually at their peak.
With summer bringing even hotter and drier weather, authorities say they are expecting more wildfires.