Most of these fires are started by arcing power lines from high winds. Jeez.
Park service says this about wild land fires. May be different in counties in soCal
Humans and Wildfire
As many as 90 percent of wildland fires in the United States are caused by humans. Some human-caused fires result from campfires left unattended, the burning of debris, negligently discarded cigarettes and intentional acts of arson. The remaining 10 percent are started by lightning or lava.