This is an archived article and the information in the article may be outdated. Please look at the time stamp on the story to see when it was last updated.

Dear Tom,
What’s the earliest date in the fall/winter season that Chicago has had a sub-32 degree high?
Chuck Kennell

Dear Chuck,
The city’s official 31-degree high recorded at O’Hare on Nov. 7 marked the earliest below-freezing high in nearly three decades, since a high of 24 on Nov. 3, 1991. Chicago weather historian Frank Wachowski informed us that this season’s occurrence was early, 10 days before the long-term average date of Nov. 17. Over the city’s 149-year climate record dating back to 1871, the earliest sub-freezing high on record was Oct. 25, 1887 when the mercury peaked at 29. Wachowski noted that there had been just three other October occurrences-31 on Oct. 28, 1925; 28 on Oct. 30, 1917 and 31 degrees on Oct. 31, 1873. The latest was a 25 on Jan. 1, 2013 and 12 on Jan. 1, 1924.