Sonoma County, CA Noise Ordinances: Decibel Limits (2026)

The decibel numbers that govern noise in unincorporated Sonoma County come from the General Plan Noise Element, not from a general noise ordinance. Its Table NE-2, 'Maximum Allowable Exterior Noise Exposures for Non-transportation Noise Sources,' uses statistical (percentile) descriptors measured at the property line of an adjacent noise-sensitive use. During the daytime period (7 a.m.–10 p.m.) the limits are: L50 (level exceeded 30 minutes per hour) = 50 dBA; L25 = 55 dBA; L08 = 60 dBA; and L02 (brief peaks) = 65 dBA. During the nighttime period (10 p.m.–7 a.m.) each limit is 5 dBA lower: L50 = 45, L25 = 50, L08 = 55, and L02 = 60 dBA. The County also designates an area as 'noise impacted' if exterior levels exceed 60 dB Ldn or 60 dB CNEL. Policy NE-1c reduces the Table NE-2 limits by 5 dBA for tonal noise, speech, music or recurring impulsive sounds (such as pile drivers or kennel dog barking), and allows limited upward adjustment where the existing ambient level is already higher. These are performance standards used when reviewing discretionary projects and use permits rather than a citable, on-the-spot decibel ceiling for residents. A codifier excerpt with the full table appears below.