The blaze, dubbed the Mill Fire, burned near Highway 38 and was 20 percent contained as of Saturday.
Despite the heat, firefighters were attacking the fast-moving fire which started Friday.
As crews made progress on the wildfire burning in Yucaipa, people who were evacuated were allowed to return to their homes.
One home was damaged, but officials said the fire was contained to the attic.
Officials said the fire slowed as it headed south, away from homes.
Firefighters were keeping a close eye on hot spots to make sure the brush fire wouldn't grow further. The fire was expected to be fully contained Sunday.
The cause of the fire remains under investigation.