Knox County Climate
Knox County, Illinois
Avg Annual Temp
49.9°F
Annual Precip
39.1"
Annual Snowfall
24.2"
Extreme Heat Days
14.966666666666669
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Seasonal Overview
National Comparison
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 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.