Clark County Climate
Clark County, Illinois
NOAA NCEI 1991-2020 Climate NormalsAvg Annual Temp
54.1°F
Annual Precip
45.5"
Annual Snowfall
11.9"
Extreme Heat Days
35
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Growing Season & Gardening
6b
Minimum winter temperature range for plant survival
3,839
Supports most vegetables & fruits
Seasonal Overview
National Comparison
7-Day Outlook
Forecast
Current Conditions
Air Quality
Safety
Weather Alerts
Climate Advisory: Clark County
Climate Verdict
Clark County has a mild, with an average annual temperature of 54.1°F, moderately wet with 45.5 inches of annual precipitation, occasional hot days — 35.3 per year above 90°F, light snow averaging 11.9 inches per year. This climate profile shapes everything from energy costs to outdoor recreation opportunities.
Seasonal Breakdown
Winters are cold, with January averaging 28.4°F. summers are warm — July averages 76.7°F. The 48°F seasonal variation provides noticeable but manageable change.
Outdoor & Gardening Guidance
Growing season and gardening data is currently limited for Clark County. Check the USDA Plant Hardiness Zone Map and local extension office for specific guidance.
Regional Context
Clark County closely matches the Illinois statewide average temperature of 52.8°F, it is somewhat wetter than average for Illinois.
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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Track your own weather in Clark County
Ambient Weather personal weather stations give you hyperlocal climate data.
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Data sources: NOAA National Centers for Environmental Information (NCEI), U.S. Climate Normals 1991-2020. Forecast and alert data from National Weather Service API. Air quality data from Open-Meteo.
Climate normals are 30-year averages of weather variables. Station data is aggregated to county level. Forecasts and alerts are fetched live and may change frequently. Data is informational only — not a substitute for official National Weather Service forecasts or emergency weather warnings.