San Mateo, CA Fire Regulations: Backyard Fires (2026)

There are two very different kinds of 'backyard fire' in unincorporated San Mateo County. (1) Recreational fires - small fires for cooking, warmth, or ambiance - are allowed under California Fire Code section 307.4, which is enforced by CAL FIRE / San Mateo County Fire. Such fires must be kept at least 25 feet from any structure or combustible material (15 feet for a manufactured portable outdoor fireplace), constantly attended by a responsible person until fully extinguished, and not lit when atmospheric conditions or local circumstances make them hazardous. The fire code official may prohibit recreational fires entirely during periods of high fire danger, which is common in the fire-prone Santa Cruz Mountains and coastal hills. (2) Open burning of yard waste, leaves, brush, or trash in the backyard is prohibited; the county fire department states all backyard burning is prohibited throughout San Mateo County, and BAAQMD bans burning garbage, plastics, and toxic materials at all times. Even permitted recreational wood fires are illegal on any day a Bay Area Spare the Air Alert is in effect under BAAQMD Regulation 6, Rule 3 (which applies year-round and covers campfires and bonfires). Propane and natural-gas fire features are exempt from the Spare the Air wood-burning ban. Residents in Very High Fire Hazard Severity Zones should expect tighter restrictions and seasonal burn suspensions from CAL FIRE.