"May 2007 was the 8th warmest and 23rd driest May since 1895. Statewide May precipitation in Illinois was 2.62 inches (1.65 inches below normal), and statewide temperatures were 67.3°F degrees (4.5°F above normal). Fortunately, short-term impacts of the dry weather were minimal because of abundant soil moisture from rainfall in previous months. Timely and widespread rains across northern and central Illinois over the Memorial Day weekend also provided relief for shallow-rooted corn and soybeans in those areas," 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.
For the three-month spring season (March–May), 10th warmest spring on record, statewide temperatures averaged 54.5°F (2.5°F above normal). While statewide precipitation was 9.66 inches (1.61 inches below normal), the northern half of the state received 10.22 inches (0.34 inches below normal), and the southern half received only 9.08 inches, 3.29 inches below normal. That's a concern because soils in southern Illinois are not as deep as soils in central and northern Illinois and are thus more vulnerable to dry conditions.
National Weather Service outlooks for both June and June–August call for equal chances of temperatures and precipitation above, below, or near normal across Illinois. "The Southeast is struggling with a significant drought, and abnormally dry conditions extend through Kentucky right up to the Illinois border. While not considered to be in a drought, southern Illinois certainly bears watching in coming weeks," says Angel.
Disclaimer: Data used for all statistics provided herein are from the Midwestern Regional Climate Center and are based on preliminary data.