Cold Snap Forecast for Illinois: The Next Arctic Blast
In Chicago the coldest week is usually Jan 20 to 26, with a normal low of 18°F, and the coldest night of the last 10 winters was −23°F on Jan 30, 2019.
Reading the National Weather Service forecast for Chicago.
Normals and records at Chicago O'Hare International Airport
The week with the lowest normal low at each reference station, from NOAA’s 1991 to 2020 normals, beside the coldest night of the last 10 winters, the median first freeze and the record low.
The coldest week and the coldest nights at Illinois reference stations
Station
Coldest week
Normal low
Coldest night, last 10 winters
First freeze
Record low
ChicagoChicago O'Hare International Airport, USW00094846
Jan 20 to 26
18°F
−23°FJan 30, 2019
Nov 4
−27°FJan 20, 1985records since 1958
RockfordGreater Rockford Airport, USW00094822
Jan 19 to 25
14°F
−31°FJan 31, 2019
Oct 16
−31°FJan 31, 2019records since 1951
MolineMoline Quad City International Airport, USW00014923
Jan 19 to 25
14°F
−33°FJan 31, 2019
Oct 24
−33°FJan 31, 2019records since 1943
SpringfieldSpringfield Capital Airport, USW00093822
Jan 17 to 23
19°F
−20°FJan 21, 2025
Oct 20
−24°FFeb 13, 1905records since 1901
CarbondaleCarbondale Sewage Plant, USC00111265
Jan 17 to 23
23°F
−6°FDec 23, 2022
Oct 30
−25°FJan 11, 1977records since 1898
Normals from NOAA NCEI; nightly lows from GHCN-Daily, the winters of 2016 to 2017 through 2025 to 2026.
The panel at the top of this page sets the next 7 nights at Chicago against the normal low for each date and adds the Climate Prediction Center outlook for the two weeks after. Enter a ZIP for your own town; it uses the nearest of the 5 Illinois reference stations.
At Chicago it is usually Jan 20 to 26, with a normal low of 18°F. At the other reference stations: Rockford Jan 19 to 25 (14°F), Moline Jan 19 to 25 (14°F), Springfield Jan 17 to 23 (19°F) and Carbondale Jan 17 to 23 (23°F). These are NOAA's 1991 to 2020 daily normals.
The normal low at Chicago reaches 32°F around Nov 21 and 20°F around Jan 6. The first actual freeze came around Nov 4 in the median of the last 10 winters, weeks ahead of the normal, because one clear calm night can run far below the average.
The coldest night of the last 10 winters at Chicago was −23°F on Jan 30, 2019, and the coldest night of a typical winter there was −8°F. Elsewhere: Rockford −31°F on Jan 31, 2019, Moline −33°F on Jan 31, 2019 and Springfield −20°F on Jan 21, 2025. The record at the Chicago station is −27°F, on Jan 20, 1985, in daily records since 1958.
At Chicago a typical recent winter brings 107 nights at 32°F or colder, 42 at 20°F or colder and 5 at zero or colder, the median of the last 10 seasons.
Each night's forecast low is compared with the NOAA normal low for that date at the nearest reference station. A night 20 or more degrees below normal is an arctic blast, and so is a night below zero where the normal low is 10°F or warmer. A night 10 to 19 below is a cold snap. A night 5 or more below, or a week that runs 3 or more below on average, is colder than normal, and a week 5 or more above is mild.
The normal lows and coldest weeks are NOAA's 1991 to 2020 daily climate normals for Chicago O'Hare International Airport (USW00094846), Greater Rockford Airport (USW00094822), Moline Quad City International Airport (USW00014923), Springfield Capital Airport (USW00093822) and Carbondale Sewage Plant (USC00111265). The recent winters, first dates and records come from the same stations' daily lows in NOAA's GHCN-Daily archive, the winters of 2016 to 2017 through 2025 to 2026. The 7 night forecast is the National Weather Service's and the outlook is the Climate Prediction Center's.
