Marshall County Climate
Marshall County, Illinois
NOAA NCEI 1991-2020 Climate NormalsAvg Annual Temp
52.6°F
Annual Precip
37.9"
Annual Snowfall
21.8"
Extreme Heat Days
29
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Growing Season & Gardening
5b
Minimum winter temperature range for plant survival
3,652
Supports most vegetables & fruits
Seasonal Overview
National Comparison
7-Day Outlook
Forecast
Current Conditions
Air Quality
Safety
Weather Alerts
Climate Advisory: Marshall County
Climate Verdict
Marshall County has a mild, with an average annual temperature of 52.6°F, moderate rainfall of 37.9 inches per year, occasional hot days — 28.5 per year above 90°F, moderate snowfall of 21.8 inches annually. This climate profile shapes everything from energy costs to outdoor recreation opportunities.
Seasonal Breakdown
Winters are cold, with January averaging 25.9°F. summers are warm — July averages 76.0°F. Residents experience a substantial 50°F difference between winter and summer.
Outdoor & Gardening Guidance
Growing season and gardening data is currently limited for Marshall County. Check the USDA Plant Hardiness Zone Map and local extension office for specific guidance.
Regional Context
Marshall County closely matches the Illinois statewide average temperature of 52.8°F, it is somewhat drier than average for Illinois.
Climate Profile
About Marshall County Weather
Typical Midwestern Climate in Marshall County
With an annual average temperature of 52.6°F, Marshall County sits right near the national median for temperate zones. This humid continental climate experiences distinct shifts between all four seasons throughout the year.
Matching the Illinois State Average
The county's average temperature of 52.6°F is nearly identical to the Illinois state average of 52.8°F. It ranks in the middle of the pack for state warmth, avoiding the extreme cold of the north and the heat of the south.
Drier Conditions Than Southern Neighbors
Marshall receives 37.9 inches of annual precipitation, which is lower than the state average of 41.7 inches. It remains slightly warmer than northern neighbor McHenry but sees more snowfall than central Illinois peers.
Cold Winters and Steamy Summer Days
Residents navigate 29 extreme heat days where temperatures top 90°F, concentrated during the 76.0°F July peak. Winter brings a significant 21.8 inches of snow and a January average of 25.9°F.
Prepare for Snow and Summer Humidity
Ensure your HVAC system can handle the 29 days of extreme heat each summer. With over 20 inches of snow annually, keep a reliable shovel or blower ready for winter clearing.
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.