Climate change in Jefferson County, Colorado
Since 1979, Jefferson County, Colorado has warmed 1.9°F, with 3 more days above 90°F, about the same number of nights above 70°F and 12% less precipitation a year. Its climate in 1996–2025 is most like Douglas County, CO's was in 1951–1980.
- Average temperature: +1.9°F
- Summer highs (Jun–Aug): +2.2°F
- Winter lows (Dec–Feb): +1.9°F
- Precipitation: −12%
- Wettest day of the year: −8%
- Longest dry spell: −2 days
- Days above 90°F: +3 days
- Nights above 70°F: +0 days
- Freezing nights: −15 days
- Frost-free season: +7 days
- Muggy days: +0 days
- Summer heat index (Jun–Aug): +1.9°F
- Extreme fire-weather days: +29 days
- Snowfall: −13%
- Snowy days (1 inch or more): −3 days
Changes follow the trend line through every year from 1979 to 2025. Data: NOAA nClimGrid-Daily; humidity from gridMET, adjusted to airport observations.