Illinois temperatures in January showed some very large swings in which the highs and lows tended to cancel each other out, with a monthly temperature of 26.7 degrees, or just 0.3 degrees above average, according to Illinois State Climatologist Jim Angel, of the Illinois State Water Survey at the Prairie Research Institute at the University of Illinois.
The first nine days of the month were above average, followed by four days below average, then three days above average. The second half of January started out much below average but steadily warmed, and by the month’s end the temperature was 20 degrees above average.
“While the magnitude of the swings was impressive, the pattern of warm and cold stretches is typical of winter in Illinois and represents the passage of warm and cold fronts across the region,” Angel said. “Because it may take a day or more for a system to pass through Illinois, the dates and size of the temperature departures at a particular station may not correspond to the statewide numbers, especially in far southern Illinois.”
The statewide average precipitation – rain plus water content of snow – was 0.85 inches, or 1.22 inches below average. Precipitation was uniformly light across Illinois, just under 1 inch in most places.
The January snowfall ranged from 2 to 5 inches in most locations. Western Illinois saw 5 to 7.5 inches. However, most of Illinois received below-average snowfall.
