Average Annual Precipitation for Illinois
The tables below give yearly averages for rainfall plus snowfall at cities in Illinois.
Each place has a total for the amount of precipitation it usually receives in a year. Most locations also have information on the number of days with wet weather. This includes the days when precipitation amounts to 0.01 inches (0.25 millimetres) or more.
The annual precipitation totals are averages based on weather data collected from 1981 to 2010 for the NOAA National Climatic Data Center.
You can jump to a separate table for each region of the state: Chicago Area, Northern Illinois, Central Illinois and Southern Illinois.
Chicago Area
| Days | Place | Inches | Millimetres |
|---|---|---|---|
| 116 | Aurora | 37.7 | 957 |
| 123 | Chicago Botanical Garden | 37.8 | 959 |
| 123 | Chicago Midway Airport | 39.1 | 993 |
| 124 | Chicago O'Hare Airport | 36.9 | 937 |
| 126 | Chicago University | 38.0 | 964 |
| 114 | Elgin | 37.8 | 959 |
| 121 | Joliet | 36.8 | 935 |
Northern Illinois
| Days | Place | Inches | Millimetres |
|---|---|---|---|
| 114 | Antioch | 36.7 | 932 |
| 120 | DeKalb | 37.0 | 939 |
| 97 | Dixon | 38.4 | 975 |
| 113 | Freeport | 36.1 | 916 |
| 117 | Moline | 38.0 | 964 |
| 119 | Rockford | 36.2 | 920 |
| – | Waukegan | 35.6 | 904 |
Central Illinois
| Days | Place | Inches | Millimetres |
|---|---|---|---|
| 99 | Alton | 41.3 | 1049 |
| 108 | Cahokia | 42.7 | 1085 |
| 122 | Danville | 42.0 | 1067 |
| 117 | Peoria | 36.5 | 927 |
| 111 | Quincy | 37.3 | 948 |
| 113 | Springfield | 37.4 | 951 |
| 121 | Urbana | 41.4 | 1051 |
Southern Illinois
| Days | Place | Inches | Millimetres |
|---|---|---|---|
| 106 | Cairo | 48.6 | 1235 |
| 108 | Marion | 48.5 | 1233 |
| 115 | Mt Vernon | 43.4 | 1102 |
Reference
National Climatic Data Center. NOAA's 1981-2010 Climate Normals.