Knox County Climate
Knox County, Illinois
NOAA NCEI 1991-2020 Climate NormalsAvg Annual Temp
49.9°F
Annual Precip
39.1"
Annual Snowfall
24.2"
Extreme Heat Days
15
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Growing Season & Gardening
5b
Minimum winter temperature range for plant survival
3,196
Supports most vegetables & fruits
Seasonal Overview
National Comparison
7-Day Outlook
Forecast
Current Conditions
Air Quality
Safety
Weather Alerts
Climate Advisory: Knox County
Climate Verdict
Knox County has a cool, averaging 49.9°F annually, moderate rainfall of 39.1 inches per year, rare extreme heat with only 14.966666666666667 days above 90°F annually, moderate snowfall of 24.2 inches annually. This climate profile shapes everything from energy costs to outdoor recreation opportunities.
Seasonal Breakdown
Winters are very cold — January averages 22.1°F. summers are warm — July averages 73.8°F. Residents experience a substantial 52°F difference between winter and summer.
Outdoor & Gardening Guidance
Growing season and gardening data is currently limited for Knox County. Check the USDA Plant Hardiness Zone Map and local extension office for specific guidance.
Regional Context
Knox County closely matches the Illinois statewide average temperature of 52.8°F, it is somewhat drier than average for Illinois.
Climate Profile
About Knox County Weather
Cooler than the national median
Knox County averages 49.9°F annually, which is cooler than the national median. It receives 39.1 inches of precipitation, making it a fairly typical representative of the central corn belt.
Trailing the state temperature average
The average annual temperature of 49.9°F is about three degrees cooler than the Illinois average of 52.8°F. Precipitation is also slightly lower than the state mark of 41.7 inches.
A bridge between north and south
Knox is notably warmer than Jo Daviess County, which averages 47.4°F. However, it sees about double the snowfall of Jersey County, recording 24.2 inches annually.
Four distinct seasons of weather
The county experiences 15 days of 90°F heat in the summer and a cold winter average of 25.4°F. Snowfall is moderate for Illinois, totaling 24.2 inches per year.
Prepare for typical Illinois extremes
A standard HVAC system is necessary to navigate 15 extreme heat days and freezing winter lows. Snow tires or a reliable shovel are recommended for the two feet of annual snowfall.
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.