Boulder County, CO Noise Ordinances: Quiet Hours (2026)
Quiet hours in Boulder County, CO, also called the noise ordinance, nighttime noise rules, or residential quiet time, define the hours during which excessive noise is prohibited.
Key Facts
- Daytime residential limit (7am-7pm)
- 55 dB(A)
- Nighttime residential limit (7pm-7am)
- 50 dB(A)
- Measurement point
- 10 ft from property line
- Lawn/power tool exemption
- up to 5 hp, 7am-10pm only
- Impulsive noise threshold
- 5 dB(A) below the 55/50 limit
- First-offense fine
- $30, rising to $300 max
Summary
Non-vehicle noise in unincorporated Boulder County residential areas is capped at 55 dB(A) from 7 a.m. to 7 p.m., dropping to 50 dB(A) overnight, under Ordinance No. 92-28 Sec. 1.01.050(C). Lawnmowers, snowblowers and hand tools of 5 horsepower or less are exempt between 7 a.m. and 10 p.m.
SECTION 1.01.050
Prohibited Noise Levels.
C. Sound from a non-vehicular source located in a residential area, shall not exceed the following limits:
7:00 a.m.-7 p.m. of the same day: 55 dB(A)
7:00 p.m.-7 a.m. of the following day: 50 dB(A)
E. Periodic, impulsive, or shrill noises are hereby declared unlawful when such noises are at or above a sound level of five dB(A) less than those listed in sections 1.01.050(A), (B), (C), and (D) above.
Full Breakdown
050(C) sets the county's baseline noise curfew for any non-vehicular source, such as music, machinery, generators, or a party, located in a residential area. the following morning, the ceiling drops to 50 dB(A). 'Residential area' is defined expansively in Sec. 020(A) to reach single- and multi-family dwellings, high-rise apartments, motels and hotels with limited accommodations, schools, hospitals, nursing homes, parks and open space, and even undeveloped land adjacent to a residential area regardless of its actual zoning designation. Sound is measured ten feet from the property line where it originates, per Sec.
040(C), using an ANSI-standard A-weighted meter and only when wind is calm enough (under 5 mph, or 25 mph with a wind screen) not to skew the reading. Sec. 050(E) tightens this further for periodic, impulsive, or shrill sounds, which become unlawful at just 5 dB(A) below the 55/50 dB(A) figures. , agricultural equipment used on a farm or ranch, sanctioned cultural or athletic events on government-controlled property, and any sound made by animals.
Violations & Fines
Breaching the 55/50 dB(A) residential quiet-hours cap is a Class 2 Petty Offense under Sec. 1.01.190. Officers may issue a penalty assessment under C.R.S. Sec. 16-2-201, and a conviction brings a $30 fine per violation plus court costs. Repeat violations by the same person within one year add $30 each time, up to a $300 cap.
Frequently Asked Questions
What time do quiet hours start in unincorporated Boulder County?
Can I mow my lawn or use a snowblower at night?
Does the quiet-hours limit apply to loud parties or music?
What's the fine for a quiet-hours violation?
Sources & Official References
Other rules in Boulder County
How Boulder County compares: Cities with the Strictest Noise Ordinances·Compare Boulder County to another location·View the Colorado noise ordinances overview
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