The average annual rainfall in Illinois varies by region but generally ranges from about 35 to 49 inches per year. Specifically:
- In the Chicago area, annual precipitation averages around 37.9 to 40.9 inches.
- Northern Illinois sees averages roughly between 35.3 and 40.5 inches.
- Central Illinois typically receives between 36.2 and 43.8 inches.
- Southern Illinois has the highest averages, from about 43.4 to 49.0 inches per year
Statewide, the average annual precipitation including rainfall and snowfall is approximately 39.2 inches (996 mm), placing Illinois around the 27th wettest state in the U.S.
. The southern part of Illinois generally receives more precipitation, exceeding 48 inches annually, while the northern part receives less than 32 inches on average
. Thus, the average annual rainfall in Illinois is roughly around 39 inches, with regional variation from about 35 to 49 inches depending on location within the state.
