Quiet hours in Longmont, CO — also called the noise ordinance, nighttime noise rules, or residential quiet time — define the hours during which excessive noise is prohibited.
Longmont's quiet hours run from 10:00 p.m. to 7:00 a.m. under LMC § 10.20.100 and § 10.20.110, when nighttime sound limits apply and many residential activities become prima facie unreasonable noise if audible 25 feet from the source or inside a neighbor's home.
LMC § 10.20.100 lists four activities that are deemed prima facie unreasonable noise during the 10:00 p.m. to 7:00 a.m. window: (B) nonlicensed motor vehicle engines, nonvehicular engines, and electric or pneumatic tools; (C) repair or adjustment of motor vehicles, machinery, or equipment; and (D) gatherings of persons engaged in loud and continuing activities for at least 15 minutes — all measured by being audible 25 feet from the source or inside a private residence the responsible person has no right to occupy. Amplified sound (item A) is unreasonable at any hour if audible 25 feet away. LMC § 10.20.110(A) sets the nighttime decibel ceiling at 50 dB(A) in residential, 55 dB(A) in commercial, and 75 dB(A) in industrial zones, measured at least 25 feet from the source. Daytime limits (7:00 a.m. to 10:00 p.m.) under § 10.20.110(B) are 55 / 65 / 75 dB(A) respectively.
General penalty under Longmont Municipal Court rules: up to $999.00 fine, up to 180 days imprisonment, or both per LMC § 10.20.100 / § 10.20.110 violation.
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