What is the greatest departure above normal for a Chicago high temperature?
— Jeff Miller
Chicago’s normal temperatures are revised every 10 years, so unseasonable temperatures in the past have to be compared to the normals that were in effect at that time.
We had Chicago climatologist Frank Wachowski check the records, and it appears that the 80-degree high on March 3, 1974, that was 41 degrees above the day’s normal high of 39 takes the prize.
High temperatures during the incredible run of 80s in March 2012 ran 35 to 38 degrees above normal, while highs during our current February warmth are running 30 to 35 degrees above the daily normal highs.