Updated January 16 to include graph of monthly precipitation departures.
Based on preliminary data, the statewide annual temperature for Illinois in 2010 was 52.8 degrees, 1 degree above normal. Even so, the winter months of January, February, and December were much below normal. See bar graph below.
The statewide annual precipitation for Illinois in 2010 was 40.32 inches, 1.09 inches above normal. This was far less than the 50.46 inches in 2008 and the 51.02 inches in 2009. Of course the precipitation in 2010 was not evenly distributed throughout the state. Western Illinois experienced much above normal rainfall with amounts in excess of 48 inches in some areas. Meanwhile southern Illinois struggled with drought through much of the summer and fall. Below are the maps of total precipitation and departures from normal.