Clinton County Climate
Clinton County, Illinois
Avg Annual Temp
55.7°F
Annual Precip
42.9"
Annual Snowfall
10.1"
Extreme Heat Days
31.6
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Seasonal Overview
National Comparison
Climate Profile
About Clinton County Weather
A warm, wet climate above national averages
Clinton County’s 55.7°F average temperature is significantly higher than the national median, indicating a warmer-than-average climate. Its 42.9 inches of rain also surpasses the typical precipitation seen across many U.S. counties.
Nearly three degrees warmer than the state average
As one of the warmest counties in Illinois, Clinton’s 55.7°F average is nearly three degrees higher than the state average. This warmth is a defining characteristic of its location in the southwestern part of the state.
High July heat compared to eastern neighbors
Clinton is warmer than Clark County to the northeast, and it experiences slightly less snowfall at 10.1 inches. While it has 32 extreme heat days, this is actually fewer than the 40 days recorded in neighboring Clay County.
Sizzling July peaks and light snowfall
July is particularly hot with an average of 78.2°F, the highest in this eight-county set. Winter is relatively short and mild, with temperatures averaging 33.3°F and very little snow accumulation.
Focus on high-capacity cooling for July
The high July temperatures of 78.2°F make reliable air conditioning a necessity for all households. Minimal snowfall of 10.1 inches means heavy winter equipment is rarely needed, though basic ice prep remains important.
Frequently Asked Questions
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Data source: NOAA National Centers for Environmental Information (NCEI), U.S. Climate Normals 1991-2020.
Climate normals are 30-year averages of weather variables computed from 1991 to 2020. Station data is aggregated to county level using spatial averaging. Data is informational only — not a substitute for official National Weather Service forecasts or emergency weather warnings.