textproduct: Chicago

KEY MESSAGES

- Above average temperatures continue through mid next week.

- Low chance of rain (30%) Saturday night, mainly S of US-24.

- Precipitation chances return toward the middle of next week (30-50%).

DISCUSSION

Issued at 242 PM CST Fri Feb 13 2026

The early spring-like weather pattern we've entered will persist through next workweek. This will favor above to at times well above normal temperatures (as we've seen today/Friday), but with variability in the details, along with periods of notable lake cooling.

Tonight through Saturday Night:

Plenty of sunshine and deeper mixing than had been shown on most forecast soundings resulted in a dry, breezy, and mild afternoon. Despite temps in the lower to mid 50s, dew points in the 20s should be telling in terms of another night of good radiational cooling. It certainly won't be quite as chilly as early this (Friday) morning, but localized mid 20s in outlying areas are a decent bet amidst otherwise upper 20s-low 30s outside of Chicago and mid 30s near downtown. Given that there was some reduced visibility in light ground fog early this morning, opted to add patchy fog mention into early Saturday morning away from Chicago due to forecast lows near or below the afternoon crossover temps.

On Saturday, light-variable winds in the morning, will support quick lake breeze development and propagation inland by the early afternoon. After initial warming prior to the lake breeze, temperatures will drop through the 40s and even into the upper 30s prior to sunset near the lake. Away from the lakeshore, our forecast highs are similar to those of Friday, with some upside potential if mid and high clouds moving in from the south don't filter out the sunshine too much.

A southern stream short-wave will track well south of our area Saturday night. Rain on the northern periphery of the system would reach into areas well south of I-80 (primarily near/south of the US Route 24) Saturday evening and overnight if the still consistently farther north ECMWF/EPS mean solution comes to fruition. Meanwhile, most of the remainder of the guidance has continued to favor even southern sections remaining dry. Even in a EC/EPS scenario, there likely would be a very sharp cut-off north of wherever the northern periphery of the rain sets up. As such, a gradient from ~30-40% PoPs south of US-24 to less than 10% near/north of I-80 appears reasonable.

Sunday through Thursday:

Sunday will be another unseasonably mild day away from Lake Michigan, reaching the mid and upper 50s to locally around 60F. A lake breeze shifting inland during the mid to late afternoon will limit highs some near the lake, followed by steady cooling into the 40s behind the lake breeze passage. After a quiet and mild Sunday night (mid-upper 30s), Monday looks quite mild based on progged 925 mb to 850 mb temps. Mid and high cloud cover may initially keep the pace of warming in check, but then it does appear that skies should clear early enough to support highs in the upper 50s to lower 60s (more than 20F above average) along with modestly breezy southwest winds. For reference, the current record high for Feb 16th is 58 degrees in Chicago and 57 degrees in Rockford, both set in 1921.

A backdoor cold front trailing from weak low pressure well to our northeast should shift southward Monday night into Tuesday, taking on backdoor characteristics in the process. There has been an overall trend toward the backdoor front making it farther south, though not as far south as the consistent ECMWF/EPS depiction. Nudged temperatures in the direction of the EC scenario, resulting in nearly 20 degrees colder than Monday near the lakeshore. The inland extent of lake cooling will be determined by how far south the front is able to progress before stalling out. There should be a gradient in temps for inland areas, with the warmest readings in the far south and southwest sections of the CWA.

The main sensible weather of interest next week will come Tuesday night through Thursday as trough ejection from the southwest results in broad lee cyclogenesis over the central and northern High Plains. As is to be expected, there's still plenty of uncertainty regarding the specific evolution of key features at the surface and aloft. The position and trajectory of the dominant/consolidated surface low will determine how much of the area temporarily gets into the exceptionally mild warm sector on Wednesday (highs well into the 60s). Precipitation- wise, showers (with a non-zero chance for elevated convection) are possible near or north of the system warm front Tuesday night into Wednesday morning. The cutoff south of stratiform precip over Wisconsin may be quite sharp.

A cold front should move across the area sometime on Wednesday, knocking temps down on Thursday, particularly near the lake. Details are quite muddy late in the workweek, with a signal for a follow-up short-wave arriving sometime Thursday-Thursday night. Note that any deeper synoptic system later next week will likely have well above average moisture content to work with, problematic for any areas that see heavy rain on top of thawing out but still frozen ground. While there's plenty of spread in the range of plausible solutions, an overall increased signal for precip resulted in PoPs jumping to 40-50%. Thermal profiles on most guidance members primarily point towards rain as the p-type, but at this range, certainly can't rule out wintry precip within the CWA, especially with northward extent. Friday will feature breezy northwest winds and cooler temps, but likely still above average for the date (Feb 20th).

Castro

AVIATION /18Z TAFS THROUGH 00Z SUNDAY/

Issued at 1150 AM CST Fri Feb 13 2026

Winds today will remain breezy out of the SSW with gusts near 20 kt at times. Winds then quickly ease with sunset, eventually turning light and variable overnight through the morning on Saturday. ORD and MDW may return to a prevailing easterly direction early to mid afternoon Saturday as a weak lake breeze moves inland.

Skies will be mostly clear through this evening with only a few passing high clouds at times. Radiational cooling overnight may lead to patchy shallow fog/BR development in parts of interior northern Illinois toward daybreak Saturday. Have introduced a TEMPO for 5SM BR MIFG from 9-13Z to account for this at DPA and RFD though confidence remains on the lower side. High cloud coverage then increases through the morning on Saturday associated with a passing disturbance which is expected to remain well south of the terminals, including any precipitation.

Petr

LOT WATCHES/WARNINGS/ADVISORIES

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