Recalling the July 1980 heat wave

Dear Tom,
Growing up in Chicago during the early 1980s, I remember a prolonged heat wave that was finally broken by some of the worst thunderstorms I’ve ever encountered. When did this occur?
— Brad M.,

Hanover Park
Dear Brad,
Chicago climatologist Frank Wachowski checked the record books, and it appears that you are recalling July 1980. The month had a blistering start, with 13 days of 90 degrees or higher in the first three weeks, including two days of triple-digit heat: 102 on July 7 and 101 on July 20. There were nine straight 90s from July 10 to 18. Late on July 20, severe storms swept the city and dropped temperatures more than 30 degrees. Strong winds caused power outages, and severe flooding occurred. Temperatures never got out of the 80s again the rest of the month, but the heat returned in August.