The fire broke out on Friday and on Saturday covered 38 square kilometers.
Over 6,000 people have been ordered to leave their homes in the sparsely populated and rural area.
More than 400 firefighters are battling the flames with the support of helicopters, airplanes and fire escape machines.
The conditions are difficult with heat, low humidity and vegetation as dry as tinder.
"Explosive fire development challenges firefighters," states the California State Fire Authority in a statement.
Roads closed
Early on Saturday, the fire had destroyed about ten buildings while threatening another 2,000. Several roads, including a highway, have been closed.
The cause of the fire is under investigation.
Another large fire that in July threatened the red mammoth trees in Yosemite, and moved towards the Sierra National Forest, is largely under control.
In recent years, California has been hit by increasingly large and deadly wildfires.
Climate change has made the climate drier and warmer, which will bring more and more extreme and unpredictable fires in the future.