In June 2024, suspected fireworks set Gregory Canyon on fire — just west of University Hill.If fireworks go off at your house and you’re there, Boulder law says you must try to stop them — or you can be treated as a complicitor.

Fireworks are part of the noise problem in our neighborhoods — and a fire risk in a town that sits against wildfire country. In Boulder every one of them is illegal, sparklers included.

Fireworks and the Wildfire Risk Zone

Each dot is a fireworks blast located by the sensor network; the shaded parcels are the Wildfire Risk Zone, per City of Boulder — where Boulder’s wildfire building code applies. Nearly two in three located blasts (248 of 396) went off inside it. That is a floor: the zone is drawn parcel by parcel and leaves out streets, where many fireworks are set off.

396 high-confidence detections, July 13, 2024 – September 19, 2026, from fireoverthehill.com, used with the operator’s permission (positions rounded to about 10 meters). Wildfire Risk Zone: City of Boulder Wildland-Urban Interface map layer, retrieved October 13, 2026. The fire marker is approximate (Gregory Canyon at the base of Flagstaff Road).

The live map: fireworks, heard and located

Each marker below is a blast picked up by several microphones on the Hill and located by the difference in when the sound reached each one. The map is run independently at fireoverthehill.com; we show it here because it captures what complaint records can’t — the fireworks nobody reports.

Map: fireoverthehill.com (independent; not operated by The Quiet Enjoyment Project). Shown: high-confidence detections only. Use the timeline to change the period (the map reaches back up to one year). Detections are automatic and located by microphone timing, so a few may be other sharp bangs; the sensors sit on the Hill, so the map shows where fireworks are heard, not the whole city. Open the full map →

A fire risk, not just a noise problem

• Most of University Hill is inside Boulder’s wildfire zone. The city’s own wildfire code map puts most of the Hill inside its Wildfire Risk Zone — the area where new building must meet ignition-resistant standards — running right up to the foothills.
• It has already happened here. On June 24, 2024, a fire suspected to have been started by fireworks burned in Gregory Canyon at the base of Flagstaff Road, just west of the Hill. Police found a 21-year-old suspect sitting at 12th Street and Baseline Road — on the Hill itself — and arrested him for second-degree arson. A month later, juveniles setting off fireworks were followed by a grass fire at Casey Middle School.
• Fire season is every season. Boulder County’s two most alarming recent fires came in winter and spring: the wind-driven Marshall Fire on December 30, 2021, which destroyed more than 1,000 homes, and the NCAR Fire, which prompted evacuations across south Boulder on March 26, 2022. A dry, windy November night on the Hill is not a safe night for fireworks.

The law

• Every firework is illegal in Boulder — including sparklers and fountains. Possessing, selling, storing, or setting them off is prohibited anywhere in city limits; apart from narrow exclusions (railroad signals, police and military use), only permitted public displays are exempt (B.R.C. 5-6-6). Colorado allows some “permissible” fireworks elsewhere, but state law lets cities ban them, and Boulder does (C.R.S. 24-33.5-2007).
• Up to $2,650 and 90 days in jail per violation (B.R.C. 5-2-4; the fine cap is indexed to inflation, and jail has limits for minors and vicarious liability).
• Every resident at the house is on the hook. When someone sets off fireworks on a residential property, each resident present nearby has a legal duty to take reasonable steps to stop it and, if that fails, to help police identify who did it. A resident who doesn’t is treated as a complicitor (B.R.C. 5-6-6(c)).
• If it starts a fire, it can be arson. The Gregory Canyon fire above ended in a second-degree arson arrest. For CU students, a fireworks violation can also mean a referral to Student Conduct.

Who else hears it

Fireworks sold to the public, measured at the minimum safe distance for the person setting them off (8–15 meters), peaked at about 138–141 dB — right at the 140 dB peak limit U.S. and EU workplace rules set for impulse noise. In a survey of 1,225 dogs, about half showed at least some fear of fireworks, and a few took weeks or months to recover. GPS-tracked wild geese flew 5 to 16 kilometers farther on New Year’s Eve and fed more for at least the 11 days the study followed them afterward. And VA medical centers warn that fireworks can trigger PTSD symptoms in veterans, especially those whose trauma involved explosions or gunfire.

What you can do

1. If you see fire, or sparks landing in dry grass or brush, call 911.
2. Otherwise, report fireworks to Boulder police non-emergency at 303-441-3333. Each call is logged and becomes part of the public record — the record that shows where and when this happens. How to make a call count →
3. Have fireworks you shouldn’t? CU Boulder says unused fireworks can be dropped off, no penalty, at the City of Boulder Public Safety Building, 1805 33rd St.

Sources

• Fireworks detections: fireoverthehill.com, public detection feed, July 2024 – September 2026; “high confidence” is the grade defined in the site’s map code (location error < 10); the embedded map is filtered to it.
• Wildfire zone: City of Boulder Wildland-Urban Interface Code (B.R.C. ch. 10-8.5) and its WUI map layer.
• Fires: Boulder County, Gregory Canyon fire (June 2024); City of Boulder, Casey Middle School fire (July 2024); Boulder County, Marshall Fire and NCAR Fire.
• Law: Boulder Revised Code 5-6-6 and 5-2-4; C.R.S. 24-33.5-2007; City of Boulder, fireworks regulations; CU Boulder fireworks notice (June 2026).
• Impacts: Kukulski et al., Archives of Acoustics 43(4), 2018; Riemer, PLoS ONE 14(9), 2019; Kölzsch et al., Conservation Letters 16(1), 2023, doi:10.1111/conl.12927; U.S. Department of Veterans Affairs, Fayetteville Coastal Health Care, “Fireworks and PTSD” (June 29, 2023).

This page is general information, not legal advice.