The statewide average rainfall of 5.6 inches in May, combined with the 2.8 inches in March and 7.3 inches in April, resulted in a total rainfall for this spring at 15.7 inches. That makes it the seventh wettest spring on record since 1895 and 4.3 inches above average.
The heaviest spring rains fell in southern Illinois. Cairo reported the highest total rainfall with 30.90 inches, followed by Brookport Dam with 29.19 inches, Du Quoin with 28.95 inches, and Carbondale with 27.59 inches. These numbers are slightly more than double the average spring rainfall totals.
[update June 7] I just found a CoCoRaHS observer near Anna (IL-UN-3) who reported 37.5 inches of rain during those three months. To put that in perspective, the average ANNUAL precipitation for the Anna area is 48 inches.
The statewide average temperature for this spring was 52.0 degrees, which is right on the 1971-2000 average of 52.0 degrees.
Note about “spring”: in climatology, we define spring as March – May. This definition lines up better with our ideas of spring weather than the astronomical definition of March 20 (equinox) to June 21 (solstice). In much of Illinois, spring weather starts to arrive before March 20 and summer weather starts to arrive before June 21.