Outdoor Lighting in Longmont, CO (2026)
2 verified outdoor lighting rules for Longmont, Colorado, sourced directly from the municipal code and official government pages.
Verified from official government sources
Dark Sky Rules
Longmont requires every new or replacement outdoor light fixture to be full cutoff, keeping light from escaping above the fixture, under Municipal Code § 15.05.140.G.2. Small fixtures are exempt: individual lights under 500 lumens, string lights under 150 lumens per bulb, and fixtures no warmer than 3000 Kelvin don't have to meet the full-cutoff standard.
Longmont Full Cutoff Outdoor Lighting Rule
Some RestrictionsLongmont Municipal Code § 15.05.140.G.2
2.All new and replacement light fixtures shall be full cutoff, except that light sources not exceeding 500 lumens for individual light fixtures, 150 lumens for individual lights in a light string (e.g., patio lights), and 3000 Kelvin in color temperature are not required to be full cutoff.
Light Trespass & Shielding
Longmont caps how much light can spill onto a neighboring residential lot, greenway or natural area at 0.1 footcandles at the property line under Municipal Code § 15.05.140.G.7. Fixture owners must also conceal or shield light sources to limit glare (G.3) and cut unnecessary security lighting after hours or motion-activate it (G.9).
Longmont Light Trespass Limit for Neighbors
Some RestrictionsLongmont Municipal Code § 15.05.140.G.3, G.7, G.9
3.Light sources shall be concealed or shielded to minimize the potential for glare and light pollution.4.Light fixtures shall be installed so that the luminaire angle is zero degrees (vertical to the ground).5.No light sources shall be directed toward property boundaries or adjacent rights-of-way.6.Lights, such as wallpacks, that shine outward and create direct glare are prohibited.7.The amount...
Looking for Boulder County county-wide rules?
County ordinances apply to unincorporated areas and may supplement Longmont city rules.
Outdoor Lighting in Boulder County →