textproduct: Chicago

KEY MESSAGES

- Cooler with breezy northeast winds today, especially north of Interstate 80. - Warmer temperatures in the low to mid 70s return by the middle of the week.

- A pattern change toward more opportunities for regular rainfall is set to occur toward the end of the week and into the first week of November.

DISCUSSION

Issued at 233 AM CDT Mon Oct 26 2026

A surface cold front is beginning to shift southward into far northern Illinois early this morning. This front will bring a northeasterly wind shift as it settles into southern parts of the area by late morning and afternoon. Cooler air filtering into northern Illinois on breezy northeasterly winds will result in a cooler autumn day. Temperatures will top out only in the lower 60s across northeastern Illinois before falling back into the 50s by early evening. Inland and further south, temperatures will be warmer, with highs in the 70s expected south of I-80 into central Illinois and Indiana. Skies look to remain mostly cloudy today, starting with a brief period of low cloud cover (less than 900 feet AGL) this morning, followed by persistent higher-level clouds through the rest of the day.

On Tuesday, a series of mid-level impulses originating from northern Mexico are forecast to track northeastward into the lower Great Lakes, maintaining persistent mid- and high-level clouds across the area. The threat of rain remains very low due to dry low-level air; however, a few isolated sprinkles cannot be ruled out during the afternoon and evening from high-based showers. Potential impacts and confidence remain too low to warrant a formal mention in the forecast.

A large Canadian high pressure system will settle over New England by Wednesday. Flow around this high, combined with low pressure troughing over the Plains and Upper Midwest, will return mild southerly winds to the region. Consequently, temperatures will rebound back into the 70s area-wide by Wednesday. While warmer weather will persist through the remainder of the week, there is a chance for isolated to scattered showers and possible thunderstorms late Wednesday night into Thursday ahead of an approaching cold front.

Ensemble guidance continues to indicate a pattern change late this weekend into next week as a long-wave trough develops across the western United States. This pattern could bring increased rain chances to our region during and after the upcoming weekend.

KJB

AVIATION /12Z TAFS THROUGH 18Z TUESDAY/

Issued at 631 AM CDT Mon Oct 26 2026

Key messages for the 12Z TAF period:

* IFR to LIFR cigs this morning following a cold frontal passage. Shaky confidence on a return to VFR

An area of IFR to LIFR cigs is dropping south across N IL early this morning. It's recently taken hold of ORD, DPA, and RFD and is expected to impact MDW and GYY early this morning as well. Timing on a return to VFR isn't of great confidence, but should be by mid to late morning, if not earlier.

Thereafter, expect NE winds at 10 to 15 kt subsiding to below 10 kt this evening and veering to SE Tuesday morning.

Doom

LOT WATCHES/WARNINGS/ADVISORIES

IL...None. IN...None. LM...Small Craft Advisory until 7 AM CDT Tuesday for Winthrop Harbor to Wilmette Harbor IL.

Small Craft Advisory from 10 AM this morning to 7 AM CDT Tuesday for Wilmette Harbor to Calumet Harbor IL-Calumet Harbor to Gary IN.