textproduct: Chicago

KEY MESSAGES

- Dangerous swimming conditions at Lake Michigan beaches through tonight.

- Chance of thunderstorms returns Wednesday with periodic, but low chances for the end of the week into the weekend.

- Warmer and more humid conditions expected early next week.

DISCUSSION

Issued at 132 PM CDT Mon Jun 22 2026

Northeast winds will gust into the 25 mph range through sunset this evening over land and remain gusty into tonight over Lake Michigan, allowing for high waves and dangerous swimming conditions at Lake Michigan beaches. There may be a short period late this afternoon when speeds/gusts increase a bit, before then slowly diminishing into this evening.

There will be a low chance for an isolated shower or sprinkles across northwest IL late this afternoon into this evening and also across northwest IN, also late this afternoon. Have slight chance pops but most of the area will stay dry.

An upper trough/closed low and associated weak surface low will move across the Great Lakes region Wednesday into Thursday. This will bring the next chance of showers and scattered thunderstorms to the local area on Wednesday. Still some timing differences for how soon this activity may reach the cwa, with some of the models bringing precip into the northern cwa around daybreak Wednesday morning. Additional development is possible as a cold front moves across the area on Wednesday though low confidence for coverage/timing. This front is then expected to move to central IL/central IN by Thursday morning as another wave moves east, possibly bringing showers and thunderstorms along the general vicinity of the frontal boundary. Models then show another wave for Thursday night into Friday, in the same general area. While there are periodic thunderstorm chances for the end of the week, there will also be many dry hours, especially for areas north of I-80.

Additional precip chances Friday into Saturday will signal a pattern change to warmer and more humid conditions as an upper ridge builds northeast into the Great Lakes region. As trends appear now, the best chance for thunderstorms may be in the Saturday evening through Sunday afternoon time period as the ridge builds northeast. Once it does, high temps by early next week look to reach the upper 80s/lower 90s along with dewpoints in the lower/mid 70s. cms

AVIATION /00Z TAFS THROUGH 06Z WEDNESDAY/

Issued at 642 PM CDT Mon Jun 22 2026

No significant aviation forecast concerns for the 00Z TAFs.

Terminals reside in a region of north-northeast surface flow, southeast of an area of surface high pressure across Manitoba, western Ontario and the upper Mississippi Valley. Winds currently around 15 kts will diminish with sunset, and will remain light northerly (light and variable at KDPA/KRFD farther to the west) overnight. Winds will turn more northeast with mixing after sunrise Tuesday, though will not be quite as breezy as the surface high pressure ridge edges eastward. A lake-assist will likely provide speeds around 10 kts for KORD/KMDW and KGYY by midday/afternoon, with winds eventually turning more easterly late in the day before becoming light southeast Tuesday evening.

Otherwise, VFR conditions are expected through the period.

Ratzer

LOT WATCHES/WARNINGS/ADVISORIES

IL...Beach Hazards Statement until 4 AM CDT Tuesday for ILZ006- ILZ103-ILZ104.

IN...Beach Hazards Statement until 4 AM CDT Tuesday for INZ001- INZ002.

LM...Small Craft Advisory until 1 AM CDT Tuesday for the IL nearshore waters.

Small Craft Advisory until 4 AM CDT Tuesday for the IN nearshore waters.