What are the highest and lowest temperatures ever recorded in Chicago during astronomical summer?

Dear Tom,

As we head into summer, I’m curious, what are the highest and lowest temperatures ever recorded in Chicago during astronomical summer?

Thanks,
Lee McConnell

Dear Lee,

Chicago climatologist Frank Wachowski checked the records and provided this 73-degree range for the city’s temperatures for the period between the summer solstice and the autumnal equinox defined as astronomical summer. Officially,105 degrees is the city’s all-time highest temperature recorded on July 24, 1934 while the lowest was 32-degrees logged on September 22, 1995. In many years that 32-degree low would have technically occurred in autumn, but in 1995 the autumnal equinox did not occur until 7:13 am on September 23, so it qualifies as the city’s only summer freeze. Wachowski also pointed out that the city did reach 109 degrees on July 23, 1934, but that Midway Airport reading was not official.