More stats for Chicago...
12/23/2022 is the 48th day on record with a high below 0, and the first such day since 1/30/2019.
Of the 48 days with a high below 0, only 7 of them have occurred in December.
December days with a high below 0:
12/28/1880: high -1
12/15/1901: high -2
12/13/1903: high -2
12/23/1983: high -6
12/24/1983: high -11
12/25/1983: high -5
12/23/2022: high -1