Franklin County Climate
Franklin County, Illinois
Avg Annual Temp
56.1°F
Annual Precip
45.8"
Annual Snowfall
9.8"
Extreme Heat Days
39.05
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Seasonal Overview
National Comparison
Climate Profile
About Franklin County Weather
Warm Southern Illinois Influences
Franklin County averages 56.1°F annually, making it notably warmer than the national median. This reflects a humid subtropical influence common in the southern tip of the state.
One of the State's Warmest Spots
The county's annual average of 56.1°F is over three degrees higher than the state average of 52.8°F. It consistently ranks as one of the warmest counties in Illinois.
High Precipitation in the South
At 45.8 inches of annual precipitation, Franklin is much wetter than central and northern Illinois. It shares this high-moisture profile with its neighbors in the coal belt region.
Hot Summers and Light Snow
Residents experience 39 extreme heat days reaching 90°F or higher each year. Conversely, snow is rare compared to the rest of the state, averaging only 9.8 inches annually.
Plan for High Energy Cooling
Air conditioning systems face heavy demand during the nearly 40 days of extreme heat. Light winter gear is usually sufficient, as average winter temperatures rarely drop far below freezing.
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.