"Rainfall amounts in northeastern Illinois established this as the wettest August and wettest summer since regional records began in 1895. Rainfall for northeastern Illinois (including those counties from Boone to LaSalle and eastward) averaged 11.47 inches, 7.33 inches above normal, and beat the 1987 record of 11.02 inches. JuneAugust totals thus far in this area averaged 20.05 inches, 8.02 inches above normal, and beat the 1972 record of 19.26 inches. Northwestern Illinois received 8.45 inches in August, 4.05 inches above normal and the 5th wettest on record. Its JuneAugust total was 19.18 inches, 6.69 inches above normal and the 4th wettest on record," says State Climatologist Jim Angel of the Illinois State Water Survey (http://www.sws.uiuc.edu), a division of the Illinois Department of Natural Resources.
"Many individual stations also set all-time August records, noteworthy because climate records for these locations go back more than 50 years. The list includes Elgin (15.12 inches), Peotone (14.00 inches), Rockford (13.82 inches), Peru (13.48 inches), Freeport (12.09 inches), Morris (11.94 inches), Antioch (11.41 inches), and Joliet (10.53 inches). Several other stations with much shorter records also reported impressive rainfall totals, including Genoa (15.71 inches), McHenry (12.65 inches), Chicago Botanic Garden (12.61 inches), Streamwood (11.62 inches), and Yorkville (11.17 inches)," says Angel.
Parts of southern and west-central Illinois, however, struggled with a lack of rainfall in August and still are classified as either abnormally dry or in moderate drought according to the U.S. Drought Monitor. Far southern Illinois south of I-64 received only 1.40 inches, 1.91 inches below normal. "The contrast between northern and southern Illinois was one of the strongest I have ever seen," says Angel.
August was unusually warm as well with a statewide temperature of 78.3 degrees, 4.6 degrees above normal and the 6th warmest on record. "The combination of dry conditions and hot weather really stressed crops in parts of southern and central Illinois," says Angel.
"The first 10 days of September reflect a continuation of this warm weather with a statewide temperature of 74.2 degrees, 3.6 degrees above normal. More promising is a shift in the rainfall pattern to less rainfall in northern Illinois and more in southern Illinois. The National Weather Service expects cooler and drier conditions to prevail over the next two weeks," concludes Angel.
Disclaimer: Data used for all statistics provided herein are from the Midwestern Regional Climate Center and are based on preliminary data.