Peotone Weather

National Weather Service Forecast for: Peotone, IL Issued by: National Weather Service Chicago/Romeoville, IL

Updated: Tue, 04-Aug-2026 2:46pm CDT

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Peotone, IL

This Afternoon Mostly Sunny Wednesday Showers And T-Storms Thursday Chance Showers And T-Storms Friday Partly Sunny Saturday Slight Chance Showers And T-Storms Sunday Chance Showers And T-Storms Monday Chance Showers And T-Storms   Hi 83 °F Hi 80 °F Hi 76 °F Hi 80 °F Hi 81 °F Hi 82 °F Hi 84 °F     Tonight Partly Cloudy Wednesday Night Showers And T-Storms Thursday Night Slight Chance Showers And T-Storms then Mostly Cloudy Friday Night Partly Cloudy then Slight Chance Rain Showers Saturday Night Chance Showers And T-Storms Sunday Night Chance Showers And T-Storms Monday Night Chance Showers And T-Storms   Lo 64 °F Lo 64 °F Lo 62 °F Lo 64 °F Lo 65 °F Lo 68 °F Lo 68 °F

Forecast from NOAA-NWS for Peotone, IL.

869
FXUS63 KLOT 041812
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
112 PM CDT Tue Aug 4 2026

.KEY MESSAGES...

- Episodes of showers and storms are expected in the general
  region this evening through tomorrow night. Repeated downpours
  may lead to localized flash flooding.

- Stormy conditions may continue this weekend and into early
  next week.

&&

.DISCUSSION...
Issued at 112 PM CDT Tue Aug 4 2026

The Lower Great Lakes region is located on the western fringe
of an expansive surface high pressure system centered on the
northeastern US coast and downstream of an elongated frontal
boundary extending from central Wisconsin through central Iowa
and into the Southern Plains. Meanwhile, aggregate upper-level
troughing is evident in GOES-19 water vapor imagery centered on
the northern United States. Closer to home (more or less between
the features of interest), it`s a pleasant early August day
with temperatures in the upper 70s to lower 80s, partly cloudy
skies, and a southwesterly breeze.

A subtle upper-level shortwave continues to support clusters of
showers and thunderstorms along the frontal boundary from
central Nebraska to western Iowa at press time. This activity is
poised to continue working eastward through the afternoon and
should reach the Mississippi River by this evening. In spite of
surface dew points in the upper 60s extending toward Lake
Michigan, quality moisture through the entire convective layer
wanes with eastern extent suggesting any storm this
afternoon/evening may tend to weaken while moving across
northern Illinois. Will maintain low-end (20-30%) chances for a
thunderstorm across northwestern Illinois through the evening
just to be safe.

Tonight, the broader upper-level trough is expected to shift
eastward toward the Great Lakes as an embedded upper-level jet
streak shifts into southern Ontario. Increasing low-level
confluence at the nose of a 700mb low-level jet and upper-level
diffluence in the right entrance region of the upper-level jet
streak will support the development of new showers and storms
across Iowa tonight. With time, at least some clustering should
encourage eastward propagating into northern Illinois by and
especially after daybreak. Confidence is hence increasing in a
wet morning commute across the area with clusters of showers and
storms. The intensity of storms may tend to weaken with
eastward extent by mid-morning owing to the instability axis
remaining focused near the Mississippi River, so am not
currently anticipating a severe weather or flash flood threat in
the morning. Coverage of showers and storms should then
decrease altogether from mid to late morning as the low- and
upper-level jet forcing weakens. Residual isentropic ascent
along the southeastward-drifting front may nevertheless support
a few showers in the general area through early afternoon.

During the afternoon and evening hours, yet another upper-
level shortwave embedded in the aggregate upper-level troughing
is poised to move into the Lower Great Lakes supporting another
round of showers and storms. There remains lower than average
confidence in the coverage and intensity of any
afternoon/evening round of storms owing to impacts of early-
day activity (that is, extensive cloud cover may limit the
ability for meaningful instability to develop ahead of the
wave). In scenarios where little to no instability is able to
materialize, the afternoon/evening may be characterized by
scattered showers and a few non-severe storms with a main threat
of lightning. However, if more meaningful instability is able
to develop, there remains concerns or a more widespread
convective episode including a threat for flash flooding given
ample synoptic-scale forcing within the high-PWAT regime. Any
local clustering could support a water-loaded downburst threat
as well, consistent with a Level 1/5 severe weather threat. Will
maintain higher-end PoPs (70-90%) across the area tomorrow
afternoon through the overnight hours and let future shifts make
informed adjustments based on real-time trends.

Current thinking is that the repeated rounds of showers and
storms along the frontal boundary should shove the effective
instability axis well south of our area by Thursday morning
especially if additional storms develop in Missouri Wednesday
night. So, will cautiously cut down PoPs on Thursday to
advertise low-end chances (20-50%) for additional thunderstorms
largely focused south of I-80.

Friday onward:

As aggregate upper-level troughing shifts eastward toward the
end of the week, a quasi-zonal to northwesterly upper-level flow
pattern will materialize across the Upper Great Lakes region
supporting additional waves of showers and storms. Some of these
may be rambunctious as the eastern edge of an EML plume is
repeatedly re-advected eastward atop a stalled frontal boundary
draped across the Great Lakes. Naturally, confidence in
when/where eventual thunderstorm clusters will roam is low at
this range. With that said, the pattern matches conceptual
models for threats for severe weather and flash flooding in the
general region through the weekend and into early next week.

Borchardt

&&

.AVIATION /18Z TAFS THROUGH 00Z THURSDAY/...
Issued at 1244 PM CDT Tue Aug 4 2026

Key messages for the 18Z TAF period:

* A system of showers and embedded thunderstorms progged for
  Wednesday morning, with another round possible in the late
  afternoon/evening

* Periods of MVFR possible with the rain on Wednesday,
  especially at RFD

SW winds up to around 10 kt this afternoon will subside for the
night. A system of showers with possible embedded thunderstorms
will work across northern IL on Wednesday morning. Favored time
of arrival is after 09Z at RFD and after 12Z at the Chicago
sites. Periods of MVFR vsby will be possible with the showers. A
break in precip coverage is expected during the early part of
the afternoon before a second round arrives during the late
afternoon into evening. Additional thunderstorms and periods of
MVFR will be possible.

At RFD, the favored signal is for MVFR cigs to settle overhead
with the morning precip and remain through the afternoon leading
up to the next round. MVFR cigs may find their way over
Chicagoland as well, but confidence there is lower.

Looking ahead, showers and a couple of storms may linger
through the night and into early Thursday with a signal for low
stratus and fog possibly developing Wednesday night.

Doom

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.

&&

$$

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