CHAMPAIGN, Ill. – The statewide precipitation for May was 6.87 inches, 2.25 inches above the long-term average, and the 12th wettest May on record, according to Jim Angel, Illinois State Climatologist at the Prairie Research Institute, University of Illinois.
In Morris, precipitation for the month measured 5.23 inches, according to the Weather Data Division of the Grundy County Emergency Management Agency.
The wettest May on record in Illinois was 1943, with 8.87 inches. In comparison, May 2012 was much drier, with 2.50 inches for the entire month.
The monthly precipitation totals in western Illinois are impressive. The heaviest amounts were contained in the area bound by St. Louis in the south, Springfield to the east, and Galesburg to the north. Radar-estimated precipitation amounts in those areas were as high as 12 to 15 inches.
The largest monthly total at a single site so far was at Prairie City (McDonough County) with 14.12 inches.
On the other end of the scale, somewhat drier conditions prevailed in parts of Illinois north of Interstate 80. Amounts of 3 to 5 inches were common across the region. One of the lowest monthly totals was at Freeport (Stephenson County) with 3.19 inches.
The total at Morris was bolstered by a 1.36-inch rainfall in the 24 hours preceding 8 a.m. on Tuesday, May 21. There were 15 days during the month with measurable rainfall.
The May totals brought the precipitation measurement for the year to 20.35 inches, due in part to the more than four inches of rain that fell during a two-day stretch in April, spawning flooding throughout Morris and surrounding area.
The statewide precipitation for January–May (year to date) was 23.55 inches, 7.93 inches above the long-term average and the wettest January–May on record. January–May of 2012 received only 10.87 inches of precipitation and was the 12th driest on record.
Statewide precipitation for March–May (the traditional spring months) was 16.71 inches, 5.31 inches above the long-term average, and the fifth wettest spring on record.
The wettest spring on record was 1927, with 18.59 inches. Spring 2012 was much drier with only 7.79 inches of precipitation.
The statewide average temperature for May was 63.6 degrees, just 1.1 degrees above average.
In Morris, the average temperature for the month was a bit warmer, pushing the mercury to 64.3 degrees on average.
There were two days during the month with temperatures at 90 degrees or better, including May 14, when the temperature climbed to the month’s high of 94 degrees.
The low temperature recorded last month was 36 degrees on May 12.
The Illinois State Water Survey at the University of Illinois at Urbana-Champaign is the primary agency in Illinois concerned with water and atmospheric resources.