The fire sparked in the Los Padres National Forest in San Luis Obispo County and was growing exponentially, officials warned. The area is mostly uninhabited.

The big picture: The Madre Fire had grown to 35,530 acres on Thursday afternoon — surpassing January's destructive Los Angeles-area fires to become California's largest this year, as much of the state faces hot, dry conditions that raise the wildfire risk ahead of the Fourth of July holiday.