Iroquois County Climate
Iroquois County, Illinois
NOAA NCEI 1991-2020 Climate NormalsAvg Annual Temp
50.8°F
Annual Precip
39.6"
Annual Snowfall
21.1"
Extreme Heat Days
16
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Growing Season & Gardening
5b
Minimum winter temperature range for plant survival
3,256
Supports most vegetables & fruits
Seasonal Overview
National Comparison
7-Day Outlook
Forecast
Current Conditions
Air Quality
Safety
Weather Alerts
Climate Advisory: Iroquois County
Climate Verdict
Iroquois County has a mild, with an average annual temperature of 50.8°F, moderate rainfall of 39.6 inches per year, rare extreme heat with only 15.7 days above 90°F annually, moderate snowfall of 21.1 inches annually. This climate profile shapes everything from energy costs to outdoor recreation opportunities.
Seasonal Breakdown
Winters are very cold — January averages 24.1°F. summers are warm — July averages 73.7°F. The 50°F seasonal variation provides noticeable but manageable change.
Outdoor & Gardening Guidance
Growing season and gardening data is currently limited for Iroquois County. Check the USDA Plant Hardiness Zone Map and local extension office for specific guidance.
Regional Context
Iroquois County closely matches the Illinois statewide average temperature of 52.8°F, it is somewhat drier than average for Illinois.
Climate Profile
About Iroquois County Weather
Cooler than average with typical Midwest seasons
The 50.8°F average temperature is over two degrees lower than the national median. The county experiences a moderate precipitation profile of 39.6 inches annually.
Trailing the Illinois state temperature average
Iroquois County stays cooler than the state average of 52.8°F, coming in at 50.8°F. This makes it part of the cooler northern-central Illinois belt.
Drier and cooler than its southern neighbors
With 39.6 inches of rain, it is drier than Jasper County further south. It also sees more snow than southern counties, averaging 21.1 inches a year.
Mild summers with 16 days of heat
Summer heat is relatively rare compared to southern Illinois, with only 16 days above 90°F. Winter brings a cold average of 27.2°F and 21.1 inches of snow.
Balance heating needs with moderate snow prep
Prepare for a long winter season with average January lows of 24.1°F. Maintenance for 21.1 inches of snow is necessary for safe winter travel.
Frequently Asked Questions
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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.