Clark County Climate
Clark County, Illinois
Avg Annual Temp
54.1°F
Annual Precip
45.5"
Annual Snowfall
11.9"
Extreme Heat Days
35.3
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Seasonal Overview
National Comparison
Climate Profile
About Clark County Weather
Wet and temperate compared to national averages
Clark County’s 54.1°F average temperature sits right at the national median, while its 45.5 inches of rain is higher than many U.S. counties. This creates a lush, humid environment with distinct seasonal transitions.
Warmer and wetter than the Illinois average
The county is notably warmer than the state average of 52.8°F, ranking in the upper half of Illinois for temperature. This warmth is accompanied by annual precipitation that exceeds the state average of 41.7 inches.
Higher humidity and heat than nearby Coles
Clark experiences 35 extreme heat days, which is ten more than the 25 days recorded in nearby Coles County. It also receives over five inches more annual precipitation than its neighbor to the west.
Frequent extreme heat and light snow
July averages a warm 76.7°F, contributing to the 35 days per year that reach at least 90°F. Winters remain relatively mild for Illinois, with only 11.9 inches of annual snowfall and a 31.3°F average.
Invest in moisture control and summer cooling
High annual precipitation of 45.5 inches means residents must ensure proper basement waterproofing and gutter maintenance. The 35 days of extreme heat also demand a robust cooling plan for peak summer months.
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.