San Mateo County, CA Outdoor Lighting: Dark Sky Rules (2026)

San Mateo County does not have a single comprehensive dark-sky lighting ordinance for all unincorporated areas, but the Development Code (Title 8) imposes lighting-control standards through its residential and district design standards and performance standards. The County's single-family residential design standards require that all exterior, landscape, and site lighting be designed and located so that light and glare are directed away from neighbors and confined to the site; low-level lighting directed toward the ground is encouraged, exterior lighting should be minimized, and outdoor areas should be illuminated no more than necessary for the intended activity. The standards also direct that light and glare be minimized as viewed from scenic corridors and other public view corridors. In the Coastal Zone, lighting on development is reviewed through the Coastal Development Permit process and Coastside Design Review, with the goal that all light and glare be contained on the parcel and not visible from adjacent residential uses or public views. Many discretionary permits include a standard condition restricting outdoor lighting to the number, location, and type of fixtures shown on approved plans, with all light glare contained to the subject parcel.