Has Chicago ever reached 100 degrees in May?

Dear Tom,
Has Chicago ever reached 100 degrees in May?

Rebecca S.

Dear Rebecca,
Not officially. Based on official site records, Chicago’s temperature has never reached 100 degrees in May; the month’s highest reading being 98 on May 31, 1934. But, it did reach triple digits the next day when the mercury soared to 102 on June 1. In 1934, however, the official thermometer was on campus at the University of Chicago, close to the cooling breezes of Lake Michigan. Inland, temperatures on May 31 were higher with widespread triple-digit readings. Midway Airport reached 102, Aurora 104, Joliet 101, LaSalle 105, and Rockford and Marengo both hit 107. That early season heat wave marked the beginning of a torrid “dust bowl” summer in which the city would log four official 100-degree days, while inland Midway Airport documented a record-tying 11.