Through June 1st this year the Chicago area has already officially had 18.57 inches of precipitation, which is well above the average 13.09 inches. The graph below shows a running tally of precipitation for the year, comparing the current year with the 5 wettest years ever in Chicago. As of June 1st, Chicago was running nearly 3.5 inches ahead of last year for precipitation and last year was the wettest year on record in Chicago.
More wet weather is expected during the upcoming week, with several rounds of showers and thunderstorms possible. Here's the latest 5 day total forecasted precipitation graphic from the Hydrometeorological Prediction Center.