Del Norte County, CA Noise Ordinances: Decibel Limits (2026)

The county's noise ordinance establishes specific, measurable decibel standards for unincorporated residential property. The exterior standard is 55 dB(A) from 7:00 a.m. to 10:00 p.m. and 50 dB(A) from 10:00 p.m. to 7:00 a.m. The interior standard, measured inside another dwelling, is 55 dB(A) daytime and 45 dB(A) overnight. If the noise is impact, simple-tone, speech, or music, each limit drops another 5 dB(A). The ordinance uses a duration-based test: exterior noise may not exceed the standard for more than 30 minutes in any hour, the standard plus 5 dB(A) for more than 15 minutes, plus 10 dB(A) for more than 5 minutes, plus 15 dB(A) for more than 1 minute, or plus 20 dB(A) for any period of time. Measurements use a sound level meter meeting ANSI S1.4-1983 (Type 1 or Type 2), with the reading taken at least four feet from a wall, ceiling, or floor and windows allowed open. 'Noise level' is defined as the A-weighted sound pressure level, dB(A). Ambient-noise adjustments apply where background levels are already high. These limits govern the unincorporated area only; Crescent City has its own standards.