Dear Tom,
What is the hottest day on record in Chicago?
James Walnert, Palos Hills

Dear James,
In weather records beginning on Nov. 1, 1870, Chicago’s highest temperature occurred on July 23, 1934, when the mercury hit 109 degrees at Midway Airport. However, Midway was not the official weather observation site then. The University of Chicago site, about one mile from Lake Michigan, was official and recorded a high of 94 degrees, its temperature cooled by an afternoon breeze off Lake Michigan. Using average daily temperatures as determined by the average of the day’s high and low temperatures, Chicago’s hottest day occurred on July 30, 1916. The high/low temperatures were 102 and 84 degrees, averaging 93 degrees for the full 24-hour period.