Based on the data so far, December has been colder and drier than average. The statewide temperature is a chilly 25.1 degrees and about 7 degrees below average.
Precipitation is less than an inch in northern and central Illinois, which is considered below-average, and 1-4 inches in southern Illinois, which is considered near to slightly above-average (see the first map).
So far, snowfall has been above-average for the first 18 days of December in Illinois. Snowfall amounts of 5 to 14 inches are common across Illinois (second map) with the largest snowfall departures of 8 to 12 inches in southern Illinois (third map). Some of the most impressive snowfall totals include 14.5 inches at Fairfield, 14.4 inches in Waltonville, and 13.5 inches in St. Francesville.
The upcoming winter storm is expected to bring significant amounts of rain, freezing rain, and/or snow, depending on where you are located. Keep close tabs on the weather forecast as this system develops.
Note: precipitation is both rainfall and the water content of any frozen precipitation (e.g., snow, sleet).