The average statewide temperature for January in Illinois was 21.8 degrees, 3 degrees below normal. That’s warmer than last January when the statewide temperature was only 20.3 degrees and a far cry from the record low January of 1977 when the average temperature was only 10.3 degrees.
The warmest temperature of the month was in Cairo with 67 degrees on January 1. The coldest temperature of the month was in Mt. Carroll with -20 degrees on January 21.
Snowfall was close to normal across much of the state. Amounts ranged from 4 inches in far southern Illinois to over 12 inches in parts of western and northeastern Illinois. Spring Grove, along the Illinois-Wisconsin border, reported the largest snowfall amount in the state with 15.1 inches.
While snowfall was close to normal in most areas, the statewide precipitation (rainfall + water content of snow) was only 1.23 inches, 0.7 inches below normal. Olney reported the largest monthly precipitation amount in the state with 2.81 inches.
Update: added maps for January snowfall, precipitation and temperature departures on February 4.
First Half of January – Slightly Colder than Normal
The Illinois statewide average temperature for January 1-15, 2010, was 21.5 degrees, 2.3 degrees below normal. The statewide average precipitation for the same period was 0.75 inches, 84 percent of normal. Precipitation includes both rainfall and the water content of any snowfall.
After a very active December in terms of snowfall, January has been relatively quiet so far. The only significant snowfall totals are in western Illinois and along Lake Michigan. However, the persistently cold weather means the snow has stuck around.
January – Cold Start to 2010
Based on preliminary data, the average statewide temperature for January was 21.1 degrees, 3.7 degree below normal. The statewide average precipitation for January was 1.50 inches, 0.43 inches and 22 percent below normal.
