Temperatures were expected to soar as high as 105 in the area and humidity was critically low, possibly dipping as low as 1 percent by the afternoon, said Tina Rose, a spokesman for the California Department of Forestry and Fire Protection.
"I was here at sun-up and the fire was burning like it was 3 o'clock in the afternoon. That is extreme fire behavior," Rose said, adding that the area had not burned in many years. "The slightest little spark is going to make a run and torch trees. It's just so bone dry."
The blaze destroyed three houses, damaged another and destroyed three mobile homes, a cabin, a garage and about a half-dozen vehicles, the U.S. Forest Service said in a statement Tuesday. Eleven outbuildings, five commercial buildings and several smaller structures also have been lost.
The wildfire started Monday between Palm Springs and Hemet, near the rural Riverside County community of Mountain Center and grew to more than 22 square miles by Wednesday morning. It was burning in thick brush and trees at an elevation of 5,000 to 7,500 feet.
More than 2,200 firefighters and 25 aircraft had the blaze about 10 percent contained.
It was mostly moving east toward the desert and away from small communities of homes, summer cabins and ranches in the San Jacinto Mountains.
Most of the damage occurred late Monday and early Tuesday as the fire more than doubled in size, but it was not assessed until later in the day. About 50 homes were evacuated along with Camp Ronald McDonald, which hosts programs for children with cancer and their families.
The fire also led authorities to close a pair of state highways and the Pacific Crest Trail. One of the highways reopened Wednesday.