McDonough County Climate
McDonough County, Illinois
Avg Annual Temp
51.5°F
Annual Precip
38.8"
Annual Snowfall
15.9"
Extreme Heat Days
26.1
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Seasonal Overview
National Comparison
Climate Profile
About McDonough County Weather
Consistent Temperate Weather in Western Illinois
McDonough County maintains an annual average of 51.5°F, slightly cooler than the national median. This region experiences the full range of four distinct seasons characteristic of the Midwest.
Cooler and Drier Than the Average
The county's 51.5°F average sits over a degree below the 52.8°F Illinois state average. Its annual precipitation of 38.8 inches is also about three inches less than the state benchmark.
Lighter Snowfall Than Northern Neighbors
At 15.9 inches of annual snow, McDonough gets less than half the snowfall of northern McHenry County. It shares a similar extreme heat profile with McLean, seeing about 26 days over 90°F.
Standard Midwestern Temperature Swings
January temperatures average 24.4°F, while July highs push the monthly average to 75.1°F. The county experiences roughly 26 days of extreme heat during the summer months.
Balanced Seasonal Home Maintenance
Prepare for moderate snowfall of 15.9 inches with basic winter gear. During the summer, maintain your A/C to handle nearly a month's worth of 90°F temperatures.
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.