The straddling fire in Riverside and San Bernardino counties consumed more than 23 square miles (about 60 square kilometers) of dry brush and timber, according to the California Department of Forestry and Fire Protection.
There was no lockdown early Sunday. The cause is still under investigation.
The blaze began when two adjacent fires were reported Friday night in Cherry Valley, an unincorporated area near the town of Beaumont, about 137 miles east of downtown Los Angeles.
The flames leapt along the brushy ridges and approached the houses as firefighters attacked it from the ground and from the air.
A house and two outbuildings were destroyed, Cal Fire said. No injuries were reported.
Evacuation orders and advisories have been issued for the mountain, canyon and foothills neighborhoods. Campgrounds and hiking trails have been closed in the San Gorgonio Wilderness Area of the San Bernardino National Forest.
A huge plume of smoke was visible for miles around and contributed to the poor air quality.
The mercury hit 105 degrees (41 Celsius) on Saturday in nearby Palm Springs. The National Weather Service said “dangerously warm conditions” are expected to continue due to high pressure over much of the south California.