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.
Mmmm hubby was wild land firefighter for 33 years. Yes there are firebugs but the majority of fires started are accidental. Yep a lot of human accidents but in these types of winds it’s usually arcing power lines.