The Grand Fire began Wednesday and has consumed more than 4,358 acres.
Evacuations remain in effect for Frazier Mountain High School, the Hungry Valley State Park, and Piru Creek campgrounds.
The blaze was not threatening any homes or buildings but fire officials said containing the blaze would be a difficult task due to the rugged and hard-to-reach terrain.
The cause of the fire remains under investigation.
Kern County officials say personnel from Kern, Los Angeles and Ventura counties were on hand with Cal-Fire, as well as Los Padres Forest Service, Bureau of Land Management, California State Parks and California Highway Patrol personnel.
Four water-dropping helicopters were also assisting in fighting the fire.