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San Mateo County, CA Noise Ordinances: Quiet Hours (2026)

Some Restrictions
Compiled from the official code textEditor Martyn O'NeillLast verified September 2026

Quiet hours in San Mateo County, CA, also called the noise ordinance, nighttime noise rules, or residential quiet time, define the hours during which excessive noise is prohibited.

Key Facts

Section
§ 4.88.350
Scope
Unincorporated area only
Standard
Subjective 'disturbs the peace' test
Penalty
Misdemeanor, per § 4.88.460

Summary

In unincorporated San Mateo County it's unlawful to make unreasonably loud, unnecessary, or unusual noise that disturbs a neighborhood's peace and quiet or annoys a person of normal sensitivity, day or night, under the county noise ordinance.

City-specific rules exist: Daly City has its own quiet hours rules that differ from San Mateo County's county-level regulations. If you live in Daly City, check the city-specific page instead.

Notwithstanding any other provision of this Ordinance, it shall be unlawful for any Person to willfully or negligently make or continue, or cause to be made or continued any unreasonably loud, unnecessary, or unusual noise which disturbs the peace and quiet of any neighborhood or which causes any discomfort or annoyance to any Person of normal sensitivity residing in the area. The factors which shall be considered in determining whether a violation of the provisions of this section exist include the following:

a)The sound level of the objectionable noise.b)The sound level of the background noise.c)The proximity of the noise to residential sleeping or hospital facilities.d)The nature and zoning of the area from which the noise emanates and upon which the noise impacts.e)The number of Persons affected by the noise sources.f)The time of day or night the noise occurs.g)The duration of the noise and its tonal, informational, or musical content.h)Whether the noise is continuous, recurrent, or intermittent.i)Whether the noise is produced by a commercial or non-commercial activity. (Prior code § 4955; Ord. 2803, 10/19/82)

Source: San Mateo County Code Ch. 4.88 - Noise Control (Municode)View official code

Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 47).

Full Breakdown

San Mateo County Ordinance Code § 4.88.350 makes it unlawful for anyone to willfully or negligently create noise that is unreasonably loud, unnecessary, or unusual and disturbs the peace and quiet of a neighborhood or causes discomfort to a person of normal sensitivity. Enforcement weighs nine listed factors, including the sound level, proximity to residential sleeping areas, the zoning of the area, and the time of day or night the noise occurs, so nighttime disturbances are judged more strictly. The rule applies only in the unincorporated county; incorporated cities set their own noise limits.

Violations & Fines

Any violation of the noise chapter is a misdemeanor, and each day a disturbance continues or is permitted to continue is a separate offense under § 4.88.460.

Frequently Asked Questions

Is there a fixed curfew hour for noise in unincorporated San Mateo County?
No set clock time: the ordinance bans any unreasonably loud noise that disturbs a neighborhood, weighing time of day or night as one factor.
Does this rule cover Redwood City or Daly City?
No. It governs only the unincorporated county; each city enforces its own separate noise ordinance.

Sources & Official References

Other rules in San Mateo County

All San Mateo County rules

How San Mateo County compares: Cities with the Strictest Noise Ordinances·California rules heatmap·Compare San Mateo County to another location·View the California noise ordinances overview

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Quiet Hours in Cities Across San Mateo County