San Mateo, CA Noise Ordinances: Outdoor Music (2026)

Outdoor live or recorded music at homes, ranches, wineries and event venues in the unincorporated county is governed by the same Chapter 4.88 framework as other noise. Under Section 4.88.330, sound at neighboring residences, schools, hospitals, churches and libraries may not exceed the Table I limits for the applicable period - daytime 7:00 a.m. to 10:00 p.m. or nighttime 10:00 p.m. to 7:00 a.m. - with the nighttime limits 5 dBA lower. Because the noise code provides no carve-out for parties or outdoor concerts, music continuing past 10:00 p.m. must meet the tighter nighttime standards, which is often impractical for amplified performance. Independently, Section 4.88.350 prohibits any unreasonably loud, unnecessary or unusual noise that disturbs the peace, considering factors such as proximity to sleeping or hospital facilities, the number of people affected and the time of day. Commercial venues and large gatherings may separately need County planning or special-event permits, which can attach noise conditions, but the baseline limits remain those of Chapter 4.88.