Illinois is already experiencing its wettest July-August and second wettest August on record with a few days left in August. [updated through August 30]
Based on rainfall through August 30, the statewide average rainfall for August is 6.70 inches, 3.11 inches above normal and the 2nd wettest August on record. The wettest August was 1977 with 6.86 inches.
Combine a very wet July with a very wet August, and you have the wettest July-August on record. The rainfall total of July-August was 13.55 inches, which is 5.88 inches above normal. It beat out the old record for July-August of 12.83 inches, set back in 1915. Here are the rainfall departures from normal for July-August so far.
Here are the rainfall departures from normal for July-August so far. Almost the entire state is green, meaning rainfall was above normal. The darkest shade of green in southern Illinois, south of Chicago, and northeast of St. Louis were 9 to 12 inches above normal and the area in blue in southern Illinois was 12 to 15 inches above normal.