textproduct: Chicago

KEY MESSAGES

- Possible fog along/south of I-80 tonight and possible fog north of I-80 Monday night.

- Scattered showers and a low chance (20%) of thunderstorms early Wednesday morning.

- Elevated fire danger Wednesday with westerly winds gusting to 30-35 mph.

- Additional rain chances Thursday night/Friday morning and possible rain/snow chances Friday night/Saturday.

- Above average temperatures through Thursday.

DISCUSSION

Issued at 200 PM CST Sun Feb 15 2026

Highs this afternoon are topping out in the upper 50s for most locations with a few spots tagging 60. A weak lake breeze has formed and will turn winds onshore and bring colder temps to the immediate Lake Michigan shoreline through sunset.

Fog will be a concern again overnight into Monday morning. Much of the high res guidance is showing fog developing overnight for areas south of I-80 though there is still quite a bit of uncertainty for how widespread or how dense this fog may become. Low level winds also steadily increase in the predawn hours into Monday morning, which would limit the overall fog potential. From this distance, included patchy fog mention overnight through mid morning Monday for areas along/south of I-80 and trends will need to be monitored this evening.

The increasing low level winds noted above will begin to mix to the surface by late Monday morning and gusts into the 25-30 mph are expected Monday. While some cloud cover is expected in the morning, should at least see partly cloudy skies by afternoon and probably mostly sunny skies as temps warm into the lower 60s for most areas and the stronger southwest winds will prevent a lake breeze Monday afternoon.

A weak frontal boundary is expected to sag south across northern IL Monday night into Tuesday morning and this may allow for fog to develop overnight and continue into Tuesday morning, north of I-80. While confidence is low, frontal boundaries are often the main element needed for fog development and added patchy fog for this time period. The proximity of this boundary will likely maintain southeast winds across much of the area Tuesday, keeping an onshore wind and colder temps along the IL shore of Lake Michigan. Though highs in the 50s are expected further inland.

Low pressure will move northwest across the northern Plains and northern Great Lakes Tuesday night into Wednesday bringing a chance for showers to the local area, mainly Tuesday night. Still some uncertainty for coverage with the blended pops now in the likely range. Thunder potential looks rather low but maintained slight chance (20%) mention for late Tuesday night. Current trends would suggest whatever precipitation develops will be quickly shifting east around or just after sunrise Wednesday morning.

Wednesday is then looking dry and windy with high temps warming into the mid/upper 60s and west/southwest winds gusting 30-35 mph. With relative humidity levels dropping into the 25 to 35 percent range in the afternoon, and depending on the extent of rain earlier in the morning, an elevated fire danger may develop, especially across the western half of the cwa.

Models are developing another storm system Thursday that moves across the local area Thursday night into Friday morning. There remains quite a bit of uncertainty with this system and its strength and location. But as trends look now, this may have a better chance to produce at least isolated thunderstorms for the local area as well as a higher chance/coverage for showers. Blended pops are now into the 40-60 percent range and that seems reasonable from this distance.

Beyond this time period, the overall trend looks colder with perhaps below normal temps by early next week. The transition to this possible colder pattern will likely have a storm system and precipitation nearby, possibly with some snow. cms

AVIATION /18Z TAFS THROUGH 00Z TUESDAY/

Issued at 1114 AM CST Sun Feb 15 2026

There are no key messages for the 18Z TAF period.

Expect westerly winds around 10 kt through this afternoon, going light and variable for a period this evening before establishing a SW direction later tonight. SW winds will regularly gust to around 20 kt, occasionally to around 25 kt, after mid-morning on Monday.

A signal exists for areas of fog mainly south of the terminals Monday morning. While best guess is that any impacts will stay out of reach, it's possible some MVFR vsbys or low stratus finds its way over the airfields during the morning. VFR was maintained in all TAFs for the seemingly low potential.

Doom

LOT WATCHES/WARNINGS/ADVISORIES

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