You can find 4 and 8-inch soil temperatures for Illinois on the Water Survey’s web site at www.isws.illinois.edu/warm/soiltemp.asp. These data are from a network of 19 sites around Illinois that is maintained by the Survey.
Below are the maps of what the 4-inch soil temperatures looked like on Wednesday and a year ago on the same date. This year the soil temperatures are barely above freezing in northern Illinois and barely above 40 degrees in southern Illinois. On the same date in 2012, the 4-inch soil temperatures were in the upper 50s and lower 60s across the state.