textproduct: Chicago

KEY MESSAGES

- Dry weather with seasonable temperatures are expected through much of the upcoming week.

DISCUSSION

Issued at 152 AM CDT Sun Oct 4 2026

A potent mid-level wave crossing the northern Great Lakes early this morning continues to encounter dry mid-level air across the CWA. However, the strong forcing interacting with little available moisture below modestly steep lapse rates has yielded an axis of isolated showers strong enough to result in precip reaching the surface north of I-88/290 corridor. This activity will quickly move east of the area over the next couple hours.

A cold front associated with the mid-level wave is charging eastward across central Iowa at this time and is expected to cross the CWA from northwest to southeast with no precip and few, if any, clouds mid-morning. CAA behind the front will offset some warming this afternoon, but upstream dew points in the upper 30s to mid 40s and NW gusts around 20 mph may result in modest mixing and allow temps to tag the low to mid 70s.

High pressure over Minnesota and Iowa tonight will cross the area Monday afternoon before reaching the eastern Great Lakes Monday night. Low temps in the low to mid 40s will be common tonight and Monday night outside of the core of the Chicago metro, with typically colder spots potentially falling into the upper 30s.

Broad longwave troughing across the eastern third of Canada will maintain generally WNW flow aloft across the area through the remainder of the upcoming week. After another dry cold frontal passage on Wednesday, quiet conditions will persist into early next weekend. Precip Tuesday through Saturday will be confined to a low chance of light rain with a moisture-starved wave lifting northeastward across the forecast area late Thursday night into Friday. Temps will turn seasonably warm late in the week into next weekend ahead of deep troughing developing across the western CONUS early next week.

Kluber

AVIATION /06Z TAFS THROUGH 12Z MONDAY/

Issued at 1216 AM CDT Sun Oct 4 2026

A fast-moving disturbance continues to shift eastward across the region. A few sprinkles will be possible as an arcing NE/SW band of mid-level cloud cover drifts east across the Chicago- area terminals through late tonight and will show brief VCSH mentions at ORD, MDW, and DPA to account for this.

Winds are becoming southerly at this time and will slowly veer out of the southwest overnight before turning out of the northwest with the passage of a cold front after daybreak. A few intermittent gusts up to 20 kts will be possible at times, but look too infrequent to add at this point. Light NW winds will then continue through the night into Monday morning.

Carlaw

LOT WATCHES/WARNINGS/ADVISORIES

IL...None. IN...None. LM...None.