Marshall County Climate
Marshall County, Illinois
Avg Annual Temp
52.6°F
Annual Precip
37.9"
Annual Snowfall
21.8"
Extreme Heat Days
28.5
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Seasonal Overview
National Comparison
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 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.