Firefighters have been fighting to spare homes from a growing Southern California forest fire, a day after flames came perilously close to neighbourhoods and destroyed one house.

Governor Jerry Brown declared a state of emergency for Orange and Riverside counties as the fire carved its way along ridges in Cleveland National Forest south of Los Angeles.

Some hillsides were allowed to burn under the watchful eyes of firefighters as a way to reduce fuel and make it harder for flames to jump roadways into communities if winds pick up again.

Aircraft dropped fire retardant on flames and homes as people ignoring evacuation orders used garden hoses to spray down their properties when the blaze flared Thursday evening, propelled by 20mph gusts.

It is one of nearly 20 blazes across California, which is seeing earlier, longer and more destructive wildfire seasons because of drought, warmer weather attributed to climate change and home construction deeper into forests.

Firefighters aided by cooler weather have made good progress against a blaze burning for nearly a month near Yosemite National Park in the northern part of the state.

The park was set to reopen on Tuesday after a two-week closure, park spokesman Scott Gediman said Friday.

Visitors should expect limited hours and visitor services next week as the park returns to normal, he said.

The blaze did not reach the heart of the park and instead burned in remote areas, making roads inaccessible and polluting the area with smoke.