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Montgomery County, MD Noise from Specific Sources: Car Alarm Limits (2026)

Some Restrictions
Compiled from the official code textEditor Martyn O'NeillLast verified September 2026

Key Facts

Governing law
County Code Ch. 31B, Noise Control
Emergency use
Always allowed
Daytime warning use
Must meet dBA limits
Residential nighttime limit
55 dBA
Enforcing agency
Dept. of Environmental Protection / Police

Summary

Sounding a car alarm, horn, or other vehicle signaling device on private property is banned except for emergencies or daytime warning signals within noise limits.

These county ordinances apply to unincorporated areas of Montgomery County. Incorporated cities within the county may have their own rules that take precedence over county-level regulations.

Sounding a horn or other signaling device on any motor vehicle on private property except:

(A) in an emergency; or

(B) as a danger warning signal during daytime hours if the device complies with noise level limits.

(2) Operating a sound-producing device on public streets for commercial advertising or to attract public attention.

(3) Selling anything by outcry.

(4) Loading, unloading, opening, closing or otherwise handling containers, building materials, construction equipment, or similar objects.

(5) Operating a device that produces, reproduces, or amplifies sound.

(6) Allowing an animal to create a noise disturbance.

(7) Operating power equipment mounted on a motor vehicle or operating other devices powered by a generator or a motor vehicle. (1996 L.M.C., ch. 32, § 1; 2011 L.M.C., ch. 7 , § 1.)

Editor’s note —See County Attorney Opinion dated 10/6/00 indicating that long-term parking on public streets is prohibited in certain circumstances, but not based on the size of the vehicle. See County Attorney Opinion dated 3/16/92 explaining that the Washington Metropolitan Area Transportation Authority (esp. Metrorail) is subject to the County’s noise control law, although an exemption may be obtained if it is in the public interest.

View official code

Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: 2026 S-90: Montgomery County Code contains legislation effective through May 7, 2026 | Zoning Updated Effective: April 13, 2026 | COMCOR Regulations effective as of July 1, 2026).

Full Breakdown

Montgomery County's noise control law lists sounding a horn or other signaling device on a motor vehicle on private property as an example that violates the Chapter if it exceeds noise standards or creates a disturbance. The device may sound only in an emergency, or as a daytime danger-warning signal that complies with the Chapter's dBA limits (65 dBA daytime / 55 dBA nighttime in residential noise areas). Complaints go to the Department of Environmental Protection or County Police.

Violations & Fines

Civil citation under Chapter 31B; fines escalate for repeat noise-disturbance violations.

Frequently Asked Questions

Can my car alarm go off if someone breaks in?
Yes, Section 31B-5(c)(1) exempts emergency use from the restriction on sounding a vehicle signaling device.
Is an alarm going off at night a violation?
Yes, nighttime sounding beyond an emergency isn't covered by the daytime warning-signal exception and can violate the Chapter's noise-disturbance standard.

Sources & Official References

Other rules in Montgomery County

All Montgomery County rules

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