CHAMPAIGN — Following the second warmest December on record, below-average temperatures in January were a shock to Illinoisans. The preliminary statewide average January temperature was 21.1 degrees, 5.6 degrees below the 1991–2020 average, according to Illinois State Climatologist Trent Ford at the University of Illinois’ Illinois State Water Survey.
January average temperatures ranged from the low teens in northern Illinois to the low 30s in southern Illinois, between 2 and 8 degrees below normal. Nighttime low temperatures frequently dipped below zero in central and northern Illinois, including lows of -22 degrees in Kane County and -20 degrees in Jo Daviess and Carroll counties.
Total January precipitation ranged from less than a tenth of an inch in central Illinois to over 5 inches in far southern Illinois. Most areas north of the Highway 13 corridor were 1 to 3 inches drier than normal, while the southern seven counties were 1 to 3 inches wetter than normal.
Snowfall totals going back to the start of October were between 5 and 15 inches below normal, with the highest deficits in northern and east-central Illinois.
January snowfall totals ranged from over 10 inches in parts of northern Illinois to less than half an inch in central and southern Illinois. Totals for the month were near to above normal in far western Illinois and the Chicagoland area, but were 1 to 8 inches below normal in central Illinois.
With the liquid water content of snow and rainfall taken together, the preliminary statewide average total January precipitation was 1.17 inches, 1.14 inches below the 1991–2020 average.
The most recent February outlooks from the Climate Prediction Center show elevated odds of wetter than normal conditions statewide, with slightly higher odds of warmer than normal weather in southern Illinois.
The three-month outlooks for February, March, and April together show a similar pattern of warmer and wetter than normal conditions to wrap up winter and begin climatological spring. These outlooks are still guided by La Niña conditions, but other indicators point to a wetter three-month period than the last few months.
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