Dear Tom,
I notice that Chicago’s average daily temperature bottomed out in mid January and has now begun to rise. Is there any single day that has the absolute coldest temperature?
Andy Parker

Dear Andy,
On average, the single coldest day of the year at Chicago’s O’Hare International Airport is January 23, when the average daily high and low temperatures are 31.1 and 17.9 degrees, for an average daily temperature of 24.5 degrees. On the 22nd, the averages are 31.1 and 18.0 degrees; on the 24th, the averages are 31.2 and 17.9 degrees. These averages are based on the 30-year period 1991-2020.

Chicago’s actual temperatures rarely adhere to averages, as residents of the area know very well. This is especially true during the cold season, when daily temperatures occasionally vary by 20 degrees or more from the averages.

Chicago’s average daily highest temperature occurs in the eleven-day period July 12-22, when the average daily temperature at O’Hare is 75.7 degrees.