Winnebago County Climate
Winnebago County, Illinois
Avg Annual Temp
49.4°F
Annual Precip
38.3"
Annual Snowfall
37.5"
Extreme Heat Days
14.8
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Seasonal Overview
National Comparison
Climate Profile
About Winnebago County Weather
A Cool Continental Climate Profile
Winnebago County maintains an annual average temperature of 49.4°F, placing it firmly in the humid continental zone. This average sits nearly five degrees below the national median, reflecting its northern latitude.
Cooler and Brisk Compared to Illinois Averages
The county tracks significantly cooler than the Illinois statewide average of 52.8°F. It also receives 38.3 inches of annual precipitation, which falls short of the state average of 41.7 inches.
Chillier Winters Than Central Neighbors
Winnebago experiences a cooler climate than Woodford County to the south, which averages 51.6°F annually. While it shares a similar precipitation profile with the region, its northern position leads to much heavier snowfall.
Biting Cold and Moderate Summer Heat
Winter temperatures average a frigid 24.9°F, bringing a substantial 37.5 inches of annual snow. Summers remain relatively mild with 15 extreme heat days over 90°F and a July average of 73.8°F.
Prepare for Snow and Seasonal Shifts
Residents should invest in heavy-duty snow removal equipment to handle the 37.5 inches of yearly accumulation. High-efficiency heating systems are essential to manage January temperatures that frequently drop to an average of 21.8°F.
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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.