Jersey County Climate
Jersey County, Illinois
NOAA NCEI 1991-2020 Climate NormalsAvg Annual Temp
53.4°F
Annual Precip
42.2"
Annual Snowfall
12.5"
Extreme Heat Days
29
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Growing Season & Gardening
6b
Minimum winter temperature range for plant survival
3,714
Supports most vegetables & fruits
Seasonal Overview
National Comparison
7-Day Outlook
Forecast
Current Conditions
Air Quality
Safety
Weather Alerts
Climate Advisory: Jersey County
Climate Verdict
Jersey County has a mild, with an average annual temperature of 53.4°F, moderately wet with 42.2 inches of annual precipitation, occasional hot days — 28.9 per year above 90°F, light snow averaging 12.5 inches per year. This climate profile shapes everything from energy costs to outdoor recreation opportunities.
Seasonal Breakdown
Winters are cold, with January averaging 27.8°F. summers are warm — July averages 76.2°F. The 48°F seasonal variation provides noticeable but manageable change.
Outdoor & Gardening Guidance
Growing season and gardening data is currently limited for Jersey County. Check the USDA Plant Hardiness Zone Map and local extension office for specific guidance.
Regional Context
Jersey County closely matches the Illinois statewide average temperature of 52.8°F.
Climate Profile
About Jersey County Weather
Warmer than the national median
Jersey County maintains an average annual temperature of 53.4°F, positioning it slightly above the national median for humidity and warmth. This climate represents a classic transition zone between the cooler northern states and the humid subtropics.
Above the Illinois state average
The county's 53.4°F average temperature exceeds the Illinois state average of 52.8°F. It records 42.2 inches of annual precipitation, which is slightly higher than the state-wide average of 41.7 inches.
A warmer choice than northern neighbors
Jersey County is significantly warmer than Jo Daviess County to the north, which averages only 47.4°F. While neighbors in the Chicago area face much heavier snowfall, Jersey sees a more moderate 12.5 inches annually.
Hot summers and mild winters
Summer heat is intense with 29 days per year reaching 90°F or higher. Winter remains relatively mild for the region, with an average December-to-February temperature of 30.9°F.
Prioritize cooling and rain management
Residents should invest in robust air conditioning to handle the 29 extreme heat days each year. Property owners also need reliable drainage systems to manage the 42.2 inches of annual rainfall.
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.