What’s the earliest date in the fall/winter season that Chicago has had a sub-32 degree high?
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.