Peotone Weather

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

Updated: Thu, 08-Oct-2026 10:11am CDT

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Peotone, IL

Today Sunny Friday Slight Chance Rain Showers then Slight Chance Showers And T-Storms Saturday Mostly Sunny Sunday Chance Rain Showers Columbus Day Mostly Sunny Tuesday Chance Rain Showers Wednesday Mostly Sunny   Hi 73 °F Hi 77 °F Hi 82 °F Hi 72 °F Hi 80 °F Hi 68 °F Hi 65 °F     Tonight Mostly Clear Friday Night Mostly Clear Saturday Night Mostly Cloudy then Chance Rain Showers Sunday Night Partly Cloudy Monday Night Chance Showers And T-Storms Tuesday Night Partly Cloudy Wednesday Night Partly Cloudy then Slight Chance Rain Showers   Lo 50 °F Lo 58 °F Lo 59 °F Lo 55 °F Lo 56 °F Lo 45 °F Lo 47 °F

Forecast from NOAA-NWS for Peotone, IL.

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FXUS63 KLOT 081103
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
603 AM CDT Thu Oct 8 2026

.KEY MESSAGES...

- Dry and more seasonable conditions today. Threat for
  scattered showers and perhaps a few thunderstorms in the
  region on Friday.

- Unseasonable warmth on Saturday followed by a period of
  showers Saturday night and Sunday morning mainly near and
  southeast of I-55.

&&

.DISCUSSION...
Issued at 108 AM CDT Thu Oct 8 2026

An elongated 1020 mb surface high will build across the Upper
Mississippi Valley today yielding another pleasant early fall
day. Northwesterly breezes will develop towards midday and into
this afternoon, and have inched gusts up a bit towards 20 mph
along the northeastern flanks of the high where progged deeper
mixing is forecast. Have continued to generally undercut NBM
dewpoints given the anticipated mixing today which yields
afternoon RH values into the 25 to 35 percent range. Winds will
then trend light/variable this evening as the surface high
translates overhead.

A broad region of low-level warm advection will develop and
subsequently intensify across Iowa late tonight before spilling
eastward across northern Illinois through Friday morning. Moist
upglide impinging upon the northeastern terminus of a zone of
modestly steep mid-level lapse rates will likely yield an
expansion of elevated showers and some thunderstorms. As is
typical with these types of set ups, the location of the main
moist/unstable axis remains a bit unclear. That said, global
guidance has remained fairly consistent, depicting the main zone
of mid-level saturation lifting across northern Illinois
through the afternoon. Will show scattered showers and isolated
thunderstorms in the weather grids during this period, and
suspect PoPs may have to be boosted further as hires guidance
better latches onto the salient forcing mechanisms. While the
severe weather threat is low given a dearth of instability, a
corridor of 30-40 kt effective bulk shear is forecast to develop
as a 40-50 kt 500 mb jet max scoots overhead. Some recent CAMs
have an interesting presentation to a convective conglomeration
pushing east of the Mississippi River towards midday, although
this would likely weaken with time as it outpaces the main
instability reservoir.

Any lingering activity will depart the region late Friday
afternoon/early evening. Saturday continues to look dry,
somewhat breezy, and warm, with initial high cirrus streaming
northward through the afternoon. The remnants of Isaias
interacting with a northward-advancing trough will result in a
chance for showers across parts of our area Saturday night into
Sunday morning. With such a dry antecedent airmass in place,
combined with northern Illinois remaining on the western extent
of the advancing jet stream, suggests that precipitation
coverage and amounts may end up being fairly limited in the
region with max upper jet support focusing across the Ohio River
Valley (barring any westward jog to the main synoptic scale
features).

Conditions currently look dry to start next week, but an
additional cold front will bring the next chance for a brief
period of showers to the region Monday night into Tuesday before
high pressure builds back across the area mid week.

Carlaw

&&

.AVIATION /12Z TAFS THROUGH 18Z FRIDAY/...
Issued at 603 AM CDT Thu Oct 8 2026

VFR conditions with SCT mid and upper-level cloud cover will
persist through the forecast period as high pressure drifts
across the region. WNW/NW winds up to around 10 knots are
expected today, though deep mixing mid to late afternoon will
result in sporadic gusts up to 20 knots. A lake breeze will also
shift winds NE at GYY this afternoon and potentially near MDW
toward sunset. Winds tonight will likely become light and VRB or
calm, but favor a SSE/SE through the night and especially
Thursday morning.

Kluber

&&

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

&&

$$

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