How many 80-degree days does Chicago average after July 31st? What’s been the most?
—Pat Byrne, Hoffman Estates
We posed your question to Chicago climatologist Frank Wachowski who quickly informed us that based on Chicago’s climate data, dating back to 1942 when the city’s official thermometer was moved away from the lakefront to an inland location, the city has averaged about 84 days of 80-degrees or higher each year. The city’s 80s have occurred as early as March 3, 1974, and as late as November 1,1950. Typically , about 35 (about 42 percent) of the city’s 80-degree plus days are late-season, occurring in August and beyond. The fewest number of late-season 80s were 19 in 1992 and 21 in 2009, while the most were 56 in 1947, followed by 48 in 2021 and 1963 and 47 in 2005.