St. Charles County, MO Noise Ordinances: Decibel Limits (2026)
Key Facts
- Industrial limit, daytime
- 60 dB(A), 8 AM–10 PM
- Industrial limit, nighttime
- 55 dB(A), 10 PM–8 AM
- Light industrial limit
- 55 dB(A) day / 50 dB(A) night
- Max fine
- $1,000 per day
- Enforced by
- Code Enforcement, County Counselor
Summary
County code sets numeric decibel ceilings by zone, with industrial and light-industrial properties allowed louder sound than residential or commercial areas, measured at the property line.
Noise measured or registered as provided herein from any source not exempted by this Section at a level which is equal to or in excess of the dB(A) established for the time period and zones listed below is declared to be excessive, unusual, loud and unnecessary: ... Light industrial 55 dB(A) / 50 dB(A) ... Industrial 60 dB(A) / 55 dB(A) ... the aforementioned zones shall be defined as set forth in the Unified Development ordinance.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: rev 4863880; v61 updated 2026-05-11; through 05-11-2026).
Full Breakdown
Under Section 210.205, noise measured at the source property line is declared excessive once it equals or exceeds the dB(A) ceiling set for the applicable zone and time period. Light industrial zones are capped at 55 dB(A) from 8:00 AM to 10:00 PM and 50 dB(A) from 10:00 PM to 8:00 AM; industrial zones are capped at 60 dB(A) daytime and 55 dB(A) nighttime. Measurements use an A-weighted sound level meter meeting ANSI standards, taken in wind under 5 mph (25 mph with a windscreen). Zone boundaries follow the Unified Development Ordinance, and when a noise source can be measured from more than one zone, the more restrictive zone's limit controls.
Violations & Fines
Misdemeanor in the unincorporated county, fined up to $1,000; each day the noise continues is a separate offense. Building and Code Enforcement officers and law enforcement may enforce; the County Counselor prosecutes.
Frequently Asked Questions
How is industrial noise measured in St. Charles County?
Can a factory be louder at night in an industrial zone?
Sources & Official References
Other rules in St. Charles County
Compare St. Charles County to another location·View the Missouri noise ordinances overview
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