textproduct: Chicago

KEY MESSAGES

- Brief bout of very cold temperatures through Thursday night.

DISCUSSION

Issued at 133 PM CST Wed Dec 3 2025

Through Friday Night:

Cold front is moving into our northwestern CWA early this afternoon with areas of light snow and flurries ahead of the front along with some transient bands of beefier snow with larger snowflakes at times. This snow should end as cold front moves through, with some guidance continuing to suggest there'll be a loss of ice nuclei and potential for some DZ/FZDZ southern CWA early this evening.

In the wake of the front, low level cold air advection will send temps tumbling tonight. As the column cools, cloud temps within the lingering post frontal stratocumulus will drop as well, dipping solidly into the range of ice being present. Pretty common in these situations to get some very light snow or flurries to leak out of these cold air stratocumulus clouds. Have introduced some flurries into the grids tonight behind the front.

Low temperatures tonight may not occur until a couple of hours past sunrise Thursday as robust cold air advection likely continues a slow temp fall beyond sunrise. Gusty northwest winds will push wind chills below zero late tonight and Thursday morning. Despite plenty of sunshine, Thursday will be very cold with highs struggling to reach 10 above across interior northern IL with highs into the teens in the urban heat island area of Chicago metro and downwind of Lake Michigan across extreme northwest Indiana. Diminishing winds Thursday afternoon will allow wind chills to rebound to above zero during the Day Thursday.

By early Thursday evening, guidance is in good agreement in placing a 1028-1029mb high smack dab over northern Illinois. Given the deep snowpack in place and clear skies, it is likely that temps will quickly tank after the sun sets, particularly at the typically colder locations. Wouldn't be surprising to see some of the typically cold spots drop to 5 to 10 below Thursday evening, but with nearly calm winds, wind chills shouldn't be a factor. High pressure is progged to move east of the area through the night Thursday, allowing southerly winds to develop and gradually increase. The strengthening southerly flow will send temps rising overnight, though the rise in temps will be be partially offset by the increasing winds keeping wind chills quite chilly.

- Izzi

Saturday through Wednesday:

There continues to be high uncertainty for precip chances in the extended with some mention of blended chance pops from Saturday night through the middle of next week. The one trend that appears to be emerging is there could be a clipper parade next week, with the potential that one or more of these pass north of the local area, which would potentially allow temps to moderate some. If there is precip falling with what will likely be cold ground, some mixed precip would be possible, but way too much uncertainty from this distance. cms

AVIATION /06Z TAFS THROUGH 12Z FRIDAY/

Issued at 1104 PM CST Wed Dec 3 2025

In the wake of an arctic cold front that crossed the area early last evening, NW winds gusting to around 20 knots will gradually diminish through the morning. Winds will then back SW under 10 knots mid afternoon as a surface high pressure shifts across northern Illinois. SW winds are then expected to persist through tonight. VFR conditions are favored through the period, though clear skies (at least initially) Thursday night and weak low-level warm air/moisture advection may result in developing BR/MIFG.

Kluber

CLIMATE

Issued at 542 PM CST Tue Dec 2 2025

Updated at 250 PM CST Tue Dec 2 2025

Here are the current record low temperatures for Thursday into Friday this week:

Chicago Cold High Low Thursday 12/4 13 (1991) 0 (1893) Friday 12/5 4 (2005)

Rockford Cold High Low Thursday 12/4 7 (1991) -4 (1991) Friday 12/5 -5 (2005)

- Izzi

LOT WATCHES/WARNINGS/ADVISORIES

IL...None. IN...None. LM...Small Craft Advisory until 9 AM CST Thursday for Winthrop Harbor IL to Gary IN.

Small Craft Advisory until 3 PM CST Thursday for Gary to Burns Harbor IN-Burns Harbor to Michigan City IN.