McLean County Climate
McLean County, Illinois
NOAA NCEI 1991-2020 Climate NormalsAvg Annual Temp
50.6°F
Annual Precip
38.7"
Annual Snowfall
15.5"
Extreme Heat Days
25
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Growing Season & Gardening
6a
Minimum winter temperature range for plant survival
3,264
Supports most vegetables & fruits
Seasonal Overview
National Comparison
7-Day Outlook
Forecast
Current Conditions
Air Quality
Safety
Weather Alerts
Climate Advisory: McLean County
Climate Verdict
McLean County has a mild, with an average annual temperature of 50.6°F, moderate rainfall of 38.7 inches per year, occasional hot days — 25.166666666666668 per year above 90°F, light snow averaging 15.5 inches per year. This climate profile shapes everything from energy costs to outdoor recreation opportunities.
Seasonal Breakdown
Winters are very cold — January averages 23.7°F. summers are warm — July averages 73.9°F. Residents experience a substantial 50°F difference between winter and summer.
Outdoor & Gardening Guidance
Growing season and gardening data is currently limited for McLean County. Check the USDA Plant Hardiness Zone Map and local extension office for specific guidance.
Regional Context
McLean County closely matches the Illinois statewide average temperature of 52.8°F, it is somewhat drier than average for Illinois.
Climate Profile
About McLean County Weather
Standardized Central Illinois Weather Patterns
McLean County's 50.6°F average annual temperature is slightly below the national median for temperate climates. It features reliable seasonal patterns common to the American breadbasket.
Just Below the State Average
At 50.6°F, McLean is over two degrees cooler than the Illinois state average of 52.8°F. Its 38.7 inches of annual precipitation is also lower than the state's 41.7-inch average.
Similar to Western Peers Like Mercer
McLean's average temperature of 50.6°F exactly matches Mercer County, though McLean sees less snow. It experiences 25 extreme heat days, placing it in the middle of the regional spectrum.
A Mix of Humidity and Frost
July averages reach 73.9°F, accompanied by 25 days where the mercury hits at least 90°F. Winter brings a January average of 23.7°F and about 15.5 inches of total snowfall.
Prepare for Moderate Snow and Heat
Expect roughly 15.5 inches of snow each winter, requiring basic removal tools. Check your insulation to keep the home efficient during the 25 days of extreme summer heat.
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.