Lee County Climate
Lee County, Illinois
Avg Annual Temp
48.5°F
Annual Precip
37.6"
Annual Snowfall
29.6"
Extreme Heat Days
10.933333333333332
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Seasonal Overview
National Comparison
Climate Profile
About Lee County Weather
Cooler Northern Continental Climate
Lee County's annual average temperature of 48.5°F sits below the national median, reflecting its position in the upper Midwest. The region experiences a classic continental climate with distinct, sharp seasonal transitions.
One of Illinois’ Cooler Counties
At 48.5°F, Lee County is significantly cooler than the Illinois statewide average of 52.8°F. This temperature gap is driven primarily by its cold winter months, which average just 23.8°F.
Cooler and Snowier than Southern Peers
Lee County receives 29.6 inches of snow annually, nearly double what counties in central or southern Illinois typically see. Its 37.6 inches of rain is slightly below the state average, making for a drier but colder environment.
Harsh Winters and Brief Summers
Winter dominates with a January average of 20.5°F and nearly 30 inches of annual snow. Summers are relatively mild, with only 11 days per year reaching 90°F or higher.
Prepare for Snow and Cold
Residents should invest in heavy-duty snow removal equipment and ensure homes are well-insulated for the sub-freezing winter average. Cooling needs are modest, as the county enjoys a comfortable July average of 72.4°F.
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.