Dear Tom,

I hate cold weather and try to head south every winter. Can I expect subzero temperatures before January?

Jim Chacon

Dear Jim,

Absolutely. The long-term average date for the season’s first subzero reading is January 1, so in about half the winters the first subzero day is in December, though the city has recorded a handful in November, the most recent (and the earliest on record) in 1950 when the mercury fell to minus 1 on November 23. Since 2000, the city has logged its first subzero days in December in six winters, most recently a low of minus 3 on December 26, 2017. The city’s worst-ever subzero spell occurred in December 1983. Dubbed “Chicago’s Frozen Christmas” the mercury remained below zero for 100 consecutive hours from 7 am Dec. 22 and did not rise above again until 11am Dec. 26. The lowest reading during the icy spell was minus 25 on Christmas Eve. Last winter, the city’s first subzero reading occurred on Jan. 7, 2022, when the mercury fell to minus 1.