Climate change in Clay County, Illinois
Since 1979, Clay County, Illinois has warmed 2.5°F, with 7 fewer days above 90°F, 7 more nights above 70°F and 19% more precipitation a year. Its climate in 1996–2025 is most like Pope County, IL's was in 1951–1980.
- Average temperature: +2.5°F
- Summer highs (Jun–Aug): −1.0°F
- Winter lows (Dec–Feb): +4.6°F
- Precipitation: +19%
- Wettest day of the year: +24%
- Longest dry spell: −0 days
- Days above 90°F: −7 days
- Nights above 70°F: +7 days
- Freezing nights: −21 days
- Frost-free season: +11 days
- Muggy days: +6 days
- Summer heat index (Jun–Aug): −0.8°F
- Extreme fire-weather days: +2 days
Changes follow the trend line through every year from 1979 to 2025. Data: NOAA nClimGrid-Daily; humidity from gridMET, adjusted to airport observations.