This image from the Illinois State Water Survey shows the climatological normal chances of a White Christmas, defined as 1" of snow on the ground Christmas morning. Most of central and southeast Illinois has between a 25% and 35% chance. (click image to enlarge)
Bitter cold gripped a good part of the nation for several days before Christmas. At the peak of the cold wave, temperatures fell to less than 20 below zero with wind chills of 50 to 60 below zero. Peoria reported 11 consecutive days with lows below zero, tying a record; the coldest temperature of 23 below zero on the 22nd was the 5th coldest on record in Peoria. Springfield reported a monthly record low temperature of 21 below zero on the 23rd, as did Champaign on the 22nd; Decatur had its second coldest December temperature on record with a 21 below zero reading on the 22nd.