I follow Chicago’s daily record high and low temperatures and was wondering what day of the year has recorded the greatest temperature difference between its record high and record low temperatures?
Chicago’s official temperature records began on Nov. 1, 1870, and continue to the present. We searched that database for the answer to your question and found that Jan. 20 is the answer. On that date in 1906, Chicago’s high temperature soared to 63 degrees; on the same date in 1985, the temperature crashed to -27 degrees (which is also the city’s all-time lowest temperature). This yields an incredible range of 90 degrees and stands as the greatest temperature range between the highest and lowest temperatures ever recorded on any Chicago date.