California Code, Public Resources Code - PRC § 4258

Whenever the director determines that a fire hazard exists in any area within a state responsibility area due to the presence of flammable material or cover, the director, by regulation, may designate that area as a hazardous fire area for the purpose of prohibiting the use or possession of fireworks therein.  The hazardous fire area shall include only those areas that are critical and hazardous due to the threat of wildfire to life, property, and natural resources posed by the fireworks.  The hazardous fire area shall not include areas that are the responsibility of a county which is contracting for fire protection to the director.

The regulation may designate areas where specified types of fireworks, not otherwise prohibited, are allowed for industrial, commercial, or agricultural use, for ceremonies, or for emergency signaling.