Winnebago County Climate
Winnebago County, Illinois
NOAA NCEI 1991-2020 Climate NormalsAvg Annual Temp
49.4°F
Annual Precip
38.3"
Annual Snowfall
37.5"
Extreme Heat Days
15
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Growing Season & Gardening
5b
Minimum winter temperature range for plant survival
3,083
Supports most vegetables & fruits
Seasonal Overview
National Comparison
7-Day Outlook
Forecast
Current Conditions
Air Quality
Safety
Weather Alerts
Climate Advisory: Winnebago County
Climate Verdict
Winnebago County has a cool, averaging 49.4°F annually, moderate rainfall of 38.3 inches per year, rare extreme heat with only 14.8 days above 90°F annually, moderate snowfall of 37.5 inches annually. This climate profile shapes everything from energy costs to outdoor recreation opportunities.
Seasonal Breakdown
Winters are very cold — January averages 21.8°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 Winnebago County. Check the USDA Plant Hardiness Zone Map and local extension office for specific guidance.
Regional Context
Winnebago County is 3.4°F cooler than the Illinois statewide average of 52.8°F, it is somewhat drier than average for Illinois.
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.
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.