Huge areas of wilderness have already burned and the mountain community of Idyllwild is just about empty at a time of year when it's normally booming thanks to tourism.
Residents and visitors streamed down the two highways that led down the mountain toward the larger cities of Hemet and Banning.
Temperatures are expected to linger near 100 degrees for the next two days before a weekend cooling trend.
Officials say the blaze is showing extreme behavior in an area that hasn't burned in many years.
Seven homes were destroyed or damaged by the wildfire soon after it broke out Monday. The fire is about 15 percent contained.