Dear Tom, 

The West has been getting extreme record heat this September. Has the year’s hottest weather in Chicago ever occurred in September?

Rory Simpson

Dear Rory,

It’s unusual, but it has occurred. Obviously, the vast majority of the years log their hottest days during the meteorological summer months of June, July, or August. We had Chicago weather historian Frank Wachowski check the record books and he found nine years since 1871 where the city’s hottest weather occurred in September. The most recent occurrence was in 2000, when it hit 93 degrees Sept. 1, though in 2017 the 95-degree high on September 23 tied June 12 for that year’s highest reading. Three of the nine September records are, oddly enough, on Sept. 7. In 1939 and again in 1960, highs of 100 degrees were the warmest of the year on Sept. 7, and in 1985 a 99- degree high on Sept. 7 took the honors. Wachowski found one more oddity. In just one year, 1967, the hottest day of the year occurred in May, when it hit 93 degrees May 26.