What are the historical chances of a White Christmas?
We define a “white Christmas” as having at least an inch of snow on the ground on December 25. The map below shows the odds across the state. It should come as no surprise that the highest odds are in northern Illinois. In general, the odds are about 40-60 percent in the northern third of Illinois, 20-40 percent in central Illinois, and 0-20 percent in southern Illinois.
There can be large differences between nearby sites. Snowfall is notoriously difficult to measure with blowing, drifting, and melting. Two nearby sites may have different results due to exposure to the sun and the wind as well as the dedication of the observer to report on Christmas Day.
What happened last year?
Areas north of Interstate 80 had snow on the ground Christmas morning, December 25, 2016. Chicago O’Hare reported 2 inches of snow on the ground, while Rockford reported 6 inches. The snow disappeared quickly with the mild weather in late December.
What is the most snow on Christmas Day?
Here are the largest snow depths on Christmas Day (12/25) for selected locations around the state:
- Chicago, 17 inches in 1951
- Rockford, 14 inches in 1951 and 2000
- Quad Cities, 12 inches in 1909
- Peoria, 10 inches in 1909
- Springfield, 10 inches in 1915
- Champaign-Urbana, 9 inches in 1983
- Carbondale, 9 inches in 2004
What are the odds this year?
Christmas is still 14 days away when this is being written. Single day forecasts that far out, especially for snow are too difficult to make. However, we can get a glimpse of how the models are trending for the week up to Christmas. Temperatures are expected to be near-normal; however, precipitation is expected to be below normal. Therefore, I think the odds of a white Christmas this year look very slim.