textproduct: Chicago

KEY MESSAGES

- Near to above normal temperatures with predominantly dry conditions are expected through much of this week.

DISCUSSION

Issued at 111 AM CDT Tue Oct 6 2026

Winds will turn southwesterly with increasing breezes into the afternoon as a fast-moving shortwave zips across southern Ontario. Forecast soundings suggest some occasional 25-30 mph gusts will be possible this afternoon, particularly across far northern Illinois/close to the Wisconsin state line. Dewpoint/RH trends remain a bit tricky as a plume of very dry 850-700 mb air will meander across the forecast area today. Diurnal mixing is progged to be deepest across our south, and have lowered dewpoints towards 40 based on the better performing guidance of late which results in min RH values either side of 30 percent, with higher values closer to the WI/IL state line. Winds look light enough within the driest airmass to preclude an elevated fire danger at this point.

An attendant cold front will approach the region late tonight. Ahead of the northwest wind shift, it's not out the question some shallow mist/fog develops across far northwest Illinois prior to daybreak. Coverage and magnitude of any BR looks too low to include in the grids at this time, however. In the wake of the front, modest cold advection will drive northwesterly breezes across the region through Wednesday morning and afternoon. Still fairly deep mixing should allow temperatures to climb back into the 70s, and perhaps near 80 in our far south.

High pressure returns with a modest cool down on Thursday before strengthening southwesterlies drive a warming trend into the weekend. Robust warm advection will develop Friday night into Saturday and some guidance (GFS) continues to squeeze out a little light precipitation. Associated soundings don't look overly supportive of this, however, and sub-mentionable PoPs from the NBM seem appropriate at this time.

Saturday looks dry, warm, and breezy, with highs potentially making a run into the lower 80s south of about I-80 (and mid- upper 70s elsewhere). There is some uncertainty by Sunday regarding the proximity of an area of rain associated with tropical moisture/remnants interacting with a broad upper low pushing out of the ArkLaMiss. The extended multi-model consensus continues to suggest that this activity will remain off to our south and east, and given the expansiveness and magnitude of the dry airmass overhead, will continue to show precip-free conditions in the area. Assuming precip and clouds remain shunted to our southeast, Sunday will be another warm day with highs in the upper 70s and lower 80s even up to the lake.

Shortwave ridging is forecast to build to our south early next week, and we'll remain on its northern fringes. While this may open us up to some low precip chances, most activity currently looks like it'll remain displaced just to our north.

Carlaw

AVIATION /12Z TAFS THROUGH 18Z WEDNESDAY/

Issued at 608 AM CDT Tue Oct 6 2026

VFR conditions will prevail through the period. S winds up to 10 knots will settle SSW by mid morning, then increase with frequent SSW/SW gusts over 20 knots and sporadic gusts to around 25 knots during the afternoon. Though surface winds will diminish to under 10 knots this evening, marginal LLWS is possible with SW winds briefly increasing to around 40 knots as low as 1500 feet late in the evening and early Wednesday morning. A dry cold front will then shift winds WNW/NW at around 10 knots Wednesday morning.

Kluber

LOT WATCHES/WARNINGS/ADVISORIES

IL...None. IN...None. LM...Small Craft Advisory from 1 PM this afternoon to 7 PM CDT this evening for the IL nearshore waters.