Snohomish County, WA Noise Ordinances: Vehicle Noise (2026)
Key Facts
- Unmuffled exhaust
- Banned any hour, SCC 10.01.040(1)(b)
- Stereo/music limit
- Audible 75+ ft outdoors is a violation
- Motorcycle cap
- 78 dB(A) at 35 mph or less
- Heavy truck cap
- 90 dB(A) above 35 mph
- First offense penalty
- $50 civil infraction, SCC 10.01.080(3)
- Repeat offense
- Misdemeanor, up to 90 days/$1,000
Summary
Snohomish County treats unmuffled exhaust, frequent engine testing near homes, and loud car stereos or horns as public disturbance noise, banned at any hour. Motor vehicles also face fixed decibel ceilings measured at 50 feet, from 78 dB(A) for motorcycles up to 90 dB(A) for trucks over 10,000 pounds GVWR.
(1) Public Disturbance Noises, Day and Night. Sounds resulting from the following activities, occurring at any hour of the day or night, are determined to be public disturbance noises. ... (b) The use of unmuffled exhaust systems on motor vehicles, off-road vehicles and recreational watercraft. (c) Creation of frequent, repetitive or continuous sounds in connection with starting, repairing, operating or testing of motor vehicles, off-road vehicles, or internal combustion engines in a manner that interferes with the peace and comfort of persons in rural or residential districts. (d) The frequent, repetitive or continuous sounding of any horn or siren attached to a motor vehicle, expect as a warning of danger or as specifically permitted or required by law.
Official source re-checked September 8, 2026: no newer edition of the code had been published (publisher’s edition: current through legislation passed August 12, 2026).
Full Breakdown
040(1) declares several vehicle-related sounds unlawful public disturbance noises at any hour, regardless of the quantitative decibel table: (b) the use of unmuffled exhaust systems on motor vehicles, off-road vehicles, and recreational watercraft; (c) frequent, repetitive, or continuous sounds from starting, repairing, operating, or testing motor vehicles or internal combustion engines that interfere with the peace and comfort of persons in rural or residential districts; (d) frequent or continuous sounding of a vehicle horn or siren except as a warning of danger or as legally required; and (g) comprehensible music or felt bass, including from automobile sound systems, heard inside a non-originating residence or 75 feet or more outdoors in a commercial, rural, or residential district.
020(15) excludes aircraft, watercraft, and rail vehicles. 030(4) sets maximum permissible sound levels for motor vehicles measured at 50 feet from the center of the travel lane at the posted speed: motorcycles are capped at 78 dB(A) at 35 mph or under and 82 dB(A) above 35 mph; automobiles and light trucks at 10,000 pounds GVWR or less are capped at 72/78 dB(A); and vehicles over 10,000 pounds GVWR are capped at 86/90 dB(A). 030(4) table from the general ambient noise limits.
Violations & Fines
SCC 10.01.080(3) makes a first public-disturbance violation, including unmuffled exhaust or a blaring car stereo, a civil infraction under chapter 7.80 RCW carrying a $50 penalty; a second violation of a like nature within one year is $100; and a second violation within 24 hours, or a third violation within one year, becomes a misdemeanor punishable by up to 90 days in jail and/or a fine of up to $1,000. Appeals of the administrator's quantitative-standard rulings go to the county hearing examiner under SCC 2.02, while civil infractions are contested under chapter 7.80 RCW.
Frequently Asked Questions
Is a car with a modified loud exhaust illegal in Snohomish County?
How loud can my car stereo be outside?
What decibel limit applies to trucks on county roads?
What's the penalty for a noisy vehicle in Snohomish County?
Sources & Official References
Other rules in Snohomish County
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