Climate change in Jersey County, Illinois
Since 1979, Jersey County, Illinois has warmed 2.3°F, with 2 fewer days above 90°F, 7 more nights above 70°F and 7% more precipitation a year. Its climate in 1996–2025 is most like St. Clair County, IL's was in 1951–1980.
- Average temperature: +2.3°F
- Summer highs (Jun–Aug): −0.5°F
- Winter lows (Dec–Feb): +3.9°F
- Precipitation: +7%
- Wettest day of the year: +24%
- Longest dry spell: −5 days
- Days above 90°F: −2 days
- Nights above 70°F: +7 days
- Freezing nights: −16 days
- Frost-free season: +9 days
- Muggy days: +8 days
- Summer heat index (Jun–Aug): +0.2°F
- Extreme fire-weather days: +1 days
- Snowfall: −29%
- Snowy days (1 inch or more): +0 days
Changes follow the trend line through every year from 1979 to 2025. Data: NOAA nClimGrid-Daily; humidity from gridMET, adjusted to airport observations.