Dear Tom, 
What is the highest (average) temperature ever recorded in Chicago?
Bill Langowsky

Dear Bill,
In official temperature records dating from Nov. 1, 1870, to the present, Chicago’s hottest day was on July 30, 1916, when the maximum/minimum temperatures were 102 and 84 degrees, for an average temperature of 93.0 degrees. Weather observations then were taken in downtown Chicago at the U.S. Courthouse building at 219 South Clark Street, less than one mile from Lake Michigan.

But at Midway Airport, seven miles inland from the summertime cooling effect of the lake, the highest temperature was registered on July 30, 1999, when the maximum and minimum temperatures were 104 and 84 degrees, giving a sweltering average temperature of 94.0 degrees.