Humans cause fires. According to CalFire, even as the number of wildfires in California rose due to the dry conditions brought on by climate change, the number of human-caused wildfires rose to 95% of all fires.
A good number of the most dangerous wind-driven fires were caused by downed power lines. Numerous fires start from car fires off freeways or even people pulling to the side of the road and catching the brush on fire with a hot catalytic converter.
Carelessly tossed cigarettes and homeless campfires are also frequent sources of fire in our area.