Peotone Weather

National Weather Service Forecast for: 2 Miles SE Peotone, IL Issued by: National Weather Service Chicago/Romeoville, IL

Updated: Sat, 20-Jun-2026 1:11pm CDT

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Peotone, IL

This Afternoon Sunny Sunday Rain Showers Monday Chance Rain Showers then Partly Sunny Tuesday Mostly Sunny Wednesday Chance Rain Showers then Chance Showers And T-Storms Thursday Chance Showers And T-Storms Friday Mostly Sunny   Hi 77 °F Hi 73 °F Hi 73 °F Hi 76 °F Hi 77 °F Hi 76 °F Hi 77 °F     Tonight Partly Cloudy Sunday Night Showers And T-Storms Monday Night Mostly Clear Tuesday Night Mostly Clear then Slight Chance Rain Showers Wednesday Night Chance Showers And T-Storms Thursday Night Chance Showers And T-Storms then Slight Chance Showers And T-Storms Friday Night Slight Chance Showers And T-Storms   Lo 57 °F Lo 57 °F Lo 53 °F Lo 55 °F Lo 56 °F Lo 55 °F Lo 57 °F

Hydrologic Outlook issued June 20 at 2:22PM CDT
Hydrologic Outlook issued June 20 at 3:30AM CDT
 

Forecast from NOAA-NWS for 2 Miles SE Peotone, IL.

412
FXUS63 KLOT 201900
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
200 PM CDT Sat Jun 20 2026

.KEY MESSAGES...

- A storm system is expected to bring widespread soaking
  rainfall to the area Sunday through Sunday night.

- An axis of heavy rainfall is expected on Sunday which could
  result in instances of flash flooding and river rises. Favored
  area for heaviest rainfall is south of I-80.

- Dry and seasonably cool conditions are expected to start next
  week before another stormy pattern settles in mid-late week.

&&

.DISCUSSION...
Issued at 200 PM CDT Sat Jun 20 2026

High pressure continues to reside over the Great Lakes this
afternoon which will maintain our tranquil weather conditions
through tonight. Temperatures this afternoon will top out in the
mid to upper 70s despite the breezy northwest winds before
cooling into the mid to upper 50s overnight. While the breezy
winds (gusting around 20-25 mph) will persist through sunset,
winds will ease this evening and become light and variable
overnight.

Heading into Sunday, the weather will turn more active as a
pair of shortwave troughs pivot through the area. The leading
shortwave (currently in central NE) is expected to arrive
towards the mid to late morning hours and will bring with it a
broad area of moderate rainfall. Given that instability during
the morning and early afternoon should be rather meager, little
to no lightning is expected. However, as we get later into the
afternoon and evening the second shortwave will begin to arrive
and be deepening as it does so. The deepening trough will allow
lapse rates to steepen (around 6-7 C/km) and may result in some
embedded thunderstorms developing especially near and south of
I-80.

Associated with the second shortwave will also be a developing
surface low that is forecast to traverse across central IL and
IN Sunday evening. The expected track of the surface low should
keep the northeast IL and northwest IN on the north side of the
system and thus limit the overall thunderstorm coverage despite
the aforementioned steepening lapse rates. That said, the
baroclinic zone associated with the low is expected to be draped
across the area and that will serve as the focus for additional
forcing and an enhancement in rainfall rates. Couple this
forcing with the modest instability and the high moisture
content of this system (PWATs around 1.5-1.75+ inches) and
conditions remain favorable for an axis of heavy rainfall to
materialize. The latest guidance suite continues to favor areas
south of I-80 (particularly into central IL/IN) for the greatest
heavy rain threat, but given the possible convective nature
sudden shifts in this axis may still occur. Regardless, it seems
that a swath of rain amounts in excess of 1 inch to locally 2+
inches will materialize somewhere in our southern CWA. Given
that this area has already seen decent rainfall from last weeks
storms, there is an elevated risk for flash flooding and river
rises as these showers/storms move through. For now we will be
maintaining our Hydrologic Outlook (ESF) for our southern CWA to
highlight this risk because of the lingering uncertainty in
exact rainfall placement, but if confidence grows consideration
may be given to a Flood Watch.

Finally, there is also a non-zero chance for a couple of strong
to possibly severe thunderstorms Sunday afternoon and evening
mainly along and south of a Pontiac, IL to Rensselaer, IN line.
With effective shear only expected to be around 20-30 kts and
the limited surface instability locally, the main severe threat
should stay south of our area into central IL. However, if a
more organized storm does develop then a gusty to locally
damaging wind threat may materialize.

The shortwaves and associated surface low will begin to push
east late Sunday night into Monday morning. This will in turn
allow rain to end from west to east with most locations expected
to be rain-free by mid-morning Monday. Therefore, partly cloudy
skies and seasonably cool conditions can be expected for Monday
with highs peaking in the mid-70s. Breezy northeast winds will
develop behind the departing low and persist through Monday
evening resulting in large waves and dangerous rip currents at
area beaches Sunday night through Monday night. Winds and waves
are expected to subside by Tuesday afternoon as the center of
the surface high passes overhead. So expect tranquil weather to
persist through Tuesday with temperatures being slightly warmer
in the upper 70s. However, onshore winds will keep temperatures
notably cooler (upper 60s) near the lake.

The pattern is forecast to turn stormier towards the middle and
later half of the week as west-southwest flow develops aloft.
This will result in periods of shortwaves traversing across the
Midwest and Great Lakes which in turn means more chances for
showers and thunderstorms. At this range, details on exact storm
coverage, timing, and intensity remains a bit uncertain so if
you have outdoor plans Wednesday onward be sure to check back
for updates. Otherwise, expect temperatures to gradually warm
towards more typical summer values by week`s end.

Yack

&&

.AVIATION /18Z TAFS THROUGH 00Z MONDAY/...
Issued at 1226 PM CDT Sat Jun 20 2026

Key Aviation Messages for the current TAF period:

- Breezy winds this afternoon before a weak lake breeze develops
  after 00Z

- Soaking rains reducing vis are expected Sunday late
  morning/afternoon

VFR conditions with west-northwest winds with gusts around 20
knots are expected through the afternoon. A weak lake breeze is
expected to push westward after 00Z. There is some uncertainty
in the exact time of arrival at Chicago terminals, but should be
less than 8 knots and eventually become light and variable
through the late evening.

Winds are expected to start out on Sunday out of the east-
southeast around 10 knots. The next disturbance will move in
from the southwest late morning. Rain rates are expected to
increase through the afternoon as the core of the system moves
in. Periods of soaking rains are expected in the afternoon
reducing conditions down to MVFR levels, with a chance for
IFR level cigs. Gustier winds to 20 knots are expected at times
during the heavier rain, eventually becoming northeasterly by
mid afternoon.

DK

&&

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

&&

$$

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