Montgomery County Climate
Montgomery County, Illinois
Avg Annual Temp
55.5°F
Annual Precip
42.1"
Annual Snowfall
—
Extreme Heat Days
42.4
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Seasonal Overview
National Comparison
Climate Profile
About Montgomery County Weather
Warmer and WETTER than Average
Montgomery’s average annual temperature of 55.5°F sits above the national median for temperate zones. It pairs this warmth with 42.1 inches of precipitation, creating a lush but humid environment.
Warmer Than Most of Illinois
At 55.5°F, the county is notably warmer than the Illinois state average of 52.8°F. This temperature gap reflects its position in the warmer southern-central tier of the state.
Higher Heat Than Nearby Morgan
Montgomery experiences 42 days of extreme heat annually, significantly more than the 32 days recorded in Morgan County to the northwest. It serves as a transition point into the hotter southern Illinois climate.
Intense Summers and Mild Winters
July brings an average of 77.6°F and contributes to 42 days per year where temperatures exceed 90°F. Winters stay relatively mild with a January average of 29.9°F and a winter mean of 33.1°F.
Prepare for Prolonged Heat Waves
With 42 days of extreme heat annually, high-efficiency air conditioning and adequate insulation are essential for comfort. Residents should also plan outdoor activities around the high humidity of the 42.1-inch rain cycle.
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.