McDonough County Climate
McDonough County, Illinois
NOAA NCEI 1991-2020 Climate NormalsAvg Annual Temp
51.5°F
Annual Precip
38.8"
Annual Snowfall
15.9"
Extreme Heat Days
26
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Growing Season & Gardening
6a
Minimum winter temperature range for plant survival
3,482
Supports most vegetables & fruits
Seasonal Overview
National Comparison
7-Day Outlook
Forecast
Current Conditions
Air Quality
Safety
Weather Alerts
Climate Advisory: McDonough County
Climate Verdict
McDonough County has a mild, with an average annual temperature of 51.5°F, moderate rainfall of 38.8 inches per year, occasional hot days — 26.1 per year above 90°F, light snow averaging 15.9 inches per year. This climate profile shapes everything from energy costs to outdoor recreation opportunities.
Seasonal Breakdown
Winters are very cold — January averages 24.4°F. summers are warm — July averages 75.1°F. Residents experience a substantial 51°F difference between winter and summer.
Outdoor & Gardening Guidance
Growing season and gardening data is currently limited for McDonough County. Check the USDA Plant Hardiness Zone Map and local extension office for specific guidance.
Regional Context
McDonough County closely matches the Illinois statewide average temperature of 52.8°F, it is somewhat drier than average for Illinois.
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 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.