San Mateo County, CA Outdoor Lighting: Light Trespass (2026)

Light trespass onto neighboring property is addressed in San Mateo County's Development Code (Title 8) through repeated district lighting requirements and performance standards. A standard provision across many zoning districts requires that all exterior and interior lighting be designed and located so that direct rays and glare are confined to the premises (in some commercial frontages, exterior lighting must be designed so as not to cast glare off-site). The County's performance standards for development include a glare standard: no direct or reflected glare, whether from floodlights or other sources, shall be visible; this does not preclude reasonable security lighting that is properly shielded so as not to fall onto adjoining property. Discretionary permits commonly carry a condition restricting outdoor lighting to the number, location, and type of fixtures on the approved plans, with all light glare contained to the subject parcel and not visible from any adjacent residential use. Together these provisions function as the County's light-trespass controls: lighting must stay on your own property and not spill glare onto neighbors. Complaints about light trespass are handled by Planning and Building code enforcement, particularly where a permit lighting condition is being violated.