Facts on a white Christmas in Illinois

[December 15, 2009]  CHAMPAIGN -- Every year in December, weather forecasters are asked the age-old question: Will we have a white Christmas this year? An analysis of Illinois' history shows the chances are slim, according to Jim Angel, state climatologist at the Illinois State Water Survey.

Based on averages of past reports of snow on the ground on Christmas mornings in 2001- 2008, Illinoisans living in the northern part of the state have the highest chance at 30-50 percent. Site averages indicate that Rockford and Chicago have only a 38 percent chance this year. For the remainder of the state, the chance of a white Christmas at various cities is only about 14 percent.

The chance of a snowy Christmas has decreased in the past decade compared with the 1971-2000 time period. Angel attributed this to the abundance of snow in the 1970s and the mild winters in the early 21st-century.

The Christmas Day with the most snow on the ground in recorded history was 1951, according to long-term records. Aurora had an incredible 31 inches piled up that day from 12 days of nearly nonstop snow and temperatures below freezing.

Nearby sites reported significant amounts, including Midway Airport with 17 inches, Wheaton with 19 inches, Peotone with 21 inches and Waukegan with 21. Other parts of northern Illinois had impressive amounts as well, including Morrison and Dixon, both with 25 inches, and Paw Paw with 27 inches.

This month, the National Weather Service predicts a normal amount of precipitation for December and an increased chance of colder-than-normal temperatures, which may boost the chance for snow. Still, the dream of awakening to glistening treetops on Dec. 25 is unlikely to come true.

"To have a guaranteed white Christmas in the Midwest, you have to travel to Hibbing or International Falls in Minnesota, or Marquette or Sault Ste. Marie in Michigan," Angel said.

The Illinois State Water Survey at the University of Illinois at Urbana-Champaign, under the Institute of Natural Resource Sustainability, is the primary agency in Illinois concerned with water and atmospheric resources.

[Text from file received from the Illinois State Water Survey]