BANNING, Calif. — A massive vegetation fire that was sparked Friday afternoon by a malfunctioning vehicle has now charred more than 26,000 acres in California's Inland Empire region, officials said Monday.
The Apple fire was ignited by "a diesel-fueled vehicle emitting burning carbon from the exhaust system," according to a statement from the California Department of Forestry and Fire Protection and the Riverside County Fire Department.
Crews battling the blaze, which is burning north of Cherry Valley in Riverside County, have had to contend with challenging weather conditions, with warm temperatures and strengthening afternoon winds expected.
The fire has burned 26,450 acres and was 5% contained as of Monday morning, Cal Fire said.
"Much of the fire activity is being driven by the record-low moisture content of the vegetation in the area combined with high temperatures and low relative humidity," officials wrote in an incident update. "These conditions are contributing to active fire behavior both day and night."
Officials added that the blaze – which was first reported at 4:55 p.m. Friday in the 9000 block of Oak Glen Road – is "burning in an area with no recent fire history."
Roughly 2,300 fire personnel are working to douse the flames.
Multiple evacuation orders and warnings were put in place Sunday in Riverside and San Bernardino counties. Roughly 7,800 residents in more than 2,500 households have been ordered to evacuate, officials said. The blaze has destroyed one home.
A persistent challenge for firefighters this week will be the wind, forecasters said.
Northwest winds are expected Monday, with gusts occasionally hitting 15 mph to 20 mph in the fire area, said Matt Moreland, a meteorologist with the National Weather Service in San Diego.
"Winds are going to be the main concern, obviously," he said.
Gusts were to be most potent in Monday afternoon and evening, but calmer late at night and Tuesday morning.
Although gusty conditions are expected, Moreland said fire crews should benefit from cooling temperatures later in the week, which will see highs drop by about 10 degrees from Monday to Wednesday in the burn area.
"The bad news is some gusty winds in the afternoon and evening. The good news is temperatures are going to trend cooler," he said.