Photo: Boulder Creek flood damage in 2013 (Photo by Patrick Campbell/University of Colorado)

Published: June 12, 2023

While summer in Colorado often means plenty of sunshine and great weather for outdoor activities, the summer months also bring the threat of flash floods. Flash flood risks in Boulder can be deceptive—it doesn’t have to be raining or even cloudy in the city for rain to be falling over the foothills and funneling through the canyons, down into Boulder.

It’s important that CU Boulder students, faculty and staff are prepared, so please review these health and safety reminders.

Flash floods


While flooding is a potential threat now, fire danger may become more of an issue later in the summer. Even after a wet spring, wildfires are a reality in Colorado’s forests. While many wildfires are caused by lightning strikes, others are human caused (by careless cigarette disposal, fireworks, camp fires, etc.). Use extreme caution when enjoying the outdoors, within the city of Boulder and in the surrounding areas. Make a plan to immediately leave the area if threatened by a wildfire and follow instructions from firefighting and emergency management officials.


In Boulder, flash floods are often the result of strong afternoon thunderstorms over the foothills during the summer months, which produce short but heavy rainfall. Boulder may also experience flash flooding as a result of heavy rainstorms when combined with snowmelt run-off in the springtime.

If a flash flood warning is issued, heed all instructions and stay away from Boulder Creek and other creeks and areas where flooding is occurring. Climb to higher ground immediately and avoid drains, ditches, ravines and culverts. During an emergency, the city's flood warning sirens are used to alert residents to potential danger from flooding or other immediate threats.

Throughout the summer months the Boulder Office of Emergency Management, in partnership with Boulder County and the city of Boulder, conducts audible testing of the countywide emergency sirens. The tests occur at 10 a.m. and 7 p.m. on the first Monday of the month, April through August.

For more information about personal preparedness and flood safety, visit CU Boulder Emergency Management Flood Information and the city of Boulder flood info page.

Flood watch vs. warning

  • A flood advisory means that thunderstorms have produced heavy rainfall that may result in ponding of water on roadways and in low-lying areas, as well as rises in small stream levels, none of which pose an immediate threat to life and property.
  • A flash flood watch indicates that conditions are favorable for flash flooding. During a watch, normal campus activity should continue, but you should tune in to local media and monitor the situation. Make a plan for yourself and be aware of your location relative to streams and creeks. Be prepared to take immediate action if a warning is issued for your area.
  • A flash flood warning means that flooding is imminent or is already occurring. You may only have a few minutes to seek safety, so take immediate action by moving to higher ground on foot as soon as a warning is issued.


While conditions in the area currently are wet, the possession or discharge of fireworks, firecrackers or skyrockets is prohibited in the city of Boulder and Boulder County. This includes but is not limited to sparklers, snaps, bottle rockets, roman candles and smoke bombs. Violations of law are enforced under the CU Student Code of Conduct and can result in sanctions such as probation, fines or educational courses.

Fireworks not only pose a significant fire risk, but they also can cause a significant noise disruption to residential areas. Even if you don’t possess or discharge fireworks, you may be held responsible for roommates’ or guests’ violations of this ordinance. 

If you find yourself in possession of unused fireworks, they can be brought to the city of Boulder Public Safety Building at 1805 33rd St. without penalty.