Climate change in Union County, Iowa
Since 1979, Union County, Iowa has warmed 2.1°F, with 3 fewer days above 90°F, about the same number of nights above 70°F and 2% more precipitation a year. Its climate in 1996–2025 is most like Davis County, IA's was in 1951–1980.
- Average temperature: +2.1°F
- Summer highs (Jun–Aug): +0.4°F
- Winter lows (Dec–Feb): +2.9°F
- Precipitation: +2%
- Wettest day of the year: −2%
- Longest dry spell: −1 days
- Days above 90°F: −3 days
- Nights above 70°F: −0 days
- Freezing nights: −10 days
- Frost-free season: +20 days
- Muggy days: +12 days
- Summer heat index (Jun–Aug): +1.1°F
- Extreme fire-weather days: +6 days
Changes follow the trend line through every year from 1979 to 2025. Data: NOAA nClimGrid-Daily; humidity from gridMET, adjusted to airport observations.