The Colorado Department of Public Health and Environment has issued the following... WHAT...Ozone Action Day Alert. WHERE...Douglas, Jefferson, Denver, western Arapahoe, western Adams, Broomfield, Boulder, Larimer, and Weld Counties WHEN...400 PM Monday August 10 to 400 PM Tuesday August 11 IMPACTS...Ozone Action Day Alert is now in effect for the Front Range Urban Corridor. Ozone concentrations in the Unhealthy for Sensitive Groups category are possible both Monday and Tuesday during the afternoon and evenings, mainly in and near the Denver metro area. For Colorado air quality conditions, forecasts, and advisories, visit: https://www.colorado.gov/airquality/colorado_summary.aspx If possible, please help us reduce ozone pollution by limiting driving gas and diesel-powered vehicles until at least 4 p.m. Tuesday, August 11, 2026. Colorado is also addressing ozone pollution through state policies. For more information about health impacts and how ozone pollution forms in Colorado, visit: https://cdphe.colorado.gov/ozone- pollution-and-your-health HEALTH INFORMATION...Increasing likelihood of respiratory symptoms and breathing discomfort in active children and adults and people with lung disease, such as asthma. Active children and adults, and people with lung disease, such as asthma, should reduce prolonged or heavy outdoor exertion.
Weather in Longmont, CO
Updated 2026-08-11 10:15 local time · ZIP codes 80501, 80503, 80504

Sunny
Active alerts
Next hours
83°1% rain
94°1% rain
96°1% rain
96°3% rain
89°6% rain
90°17% rain
94°1% rain
94°2% rain
91°1% rain
87°17% rain
79°9% rain
76°2% rain3-day weather forecast



Weather details
Sunrise, sunset and moon
Weather insights for today
Rain chance stays relatively low over the next 12 hours (up to 17%).
It feels like 79°F with winds near 2 mph.
83°F, 1% rain chance and 2 mph wind.
Visibility is around 10 mi; gusts may reach 21 mph.
Current temperature is 83°F, wind 2 mph, rain chance up to 17%.
UV index is 4. Sunscreen and sunglasses are sensible for longer outdoor time.
Longmont weather today
Sunny and 83°F in Longmont, CO. Today's high is 96°F with a 17% rain chance. Winds are around 2 mph with gusts near 7 mph. Relative humidity is 30%, pressure is 30.11 inHg, and visibility is about 10 miles.
Tonight and tomorrow in Longmont
Sunrise is at 06:08 AM and sunset is at 08:03 PM. Tomorrow's forecast calls for Sunny with a high near 96°F and a low near 63°F. The maximum rain chance is 57%.