What is the city’s longest streak of daily high and low temperatures when the mercury never dropped below 70 degrees?

Dear Tom,
What is the city’s longest streak of daily high and low temperatures when the mercury never dropped below 70 degrees?
— Brian Dunne, Westmont
Dear Brian,
It’s been nearly a century since the city logged a record 41-day stretch when the mercury never dropped below 70. The streak began on June 20, 1921, with a 70-degree low and continued through July 30, with the temperature finally dropping to 67 on July 31. During that stretch, the highest minimum temperature was 80 on July 4. In 1921, the city’s official thermometer was located downtown at the U.S. Courthouse, so the city’s heat island helped keep the minimum temperatures elevated. Since the official temperature site was moved to Midway in 1942 and to O’Hare in 1980, the longest streak of 70-degree or higher temperatures is just 12 days, recorded during the 1988 drought summer from Aug. 8-19.