Peotone Weather

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

Updated: Mon, 20-Oct-2025 4:11pm CDT

- Select Forecast - Peotone, IL Manteno, IL Beecher, IL Monee, IL Kankakee, IL Willmington, IL Braidwood, IL Manhattan, IL OakForest, IL Stelle, IL Ottawa, IL Amboy, IL Byron, IL Rockford, IL Quad Cities, IL Champaign/Urbana, IL Peoria, IL Bloomington, IL Springfield, IL Carbondale, IL Vienna, IL Culver, IN

Peotone, IL

This Afternoon Sunny Tuesday Chance Rain Showers Wednesday Partly Sunny Thursday Sunny Friday Areas Of Frost then Mostly Sunny Saturday Chance Rain Showers Sunday Chance Rain Showers   Hi 65 °F Hi 56 °F Hi 53 °F Hi 55 °F Hi 58 °F Hi 58 °F Hi 62 °F     Tonight Rain Showers Likely Tuesday Night Slight Chance Rain Showers then Mostly Cloudy Wednesday Night Mostly Clear Thursday Night Mostly Clear then Areas Of Frost Friday Night Mostly Cloudy Saturday Night Chance Rain Showers Sunday Night Slight Chance Rain Showers   Lo 46 °F Lo 42 °F Lo 35 °F Lo 33 °F Lo 42 °F Lo 46 °F Lo 48 °F

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

689
FXUS63 KLOT 201937
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
237 PM CDT Mon Oct 20 2025

.KEY MESSAGES...

- Period of rain expected mid-late evening tonight, then some
  isolated to scattered showers expected Tuesday afternoon/early
  evening.

- Strong west winds, gusting between 30-40 mph, are expected
  Tuesday afternoon with a few peak gusts to around 45 mph
  possible.

- Seasonably cool temperatures are expected the remainder of the
  upcoming work week.

&&

.DISCUSSION...
Issued at 237 PM CDT Mon Oct 20 2025

Through Tuesday Night:

Upper trough over the northern Great Plains and southern
Canadian Prairies is digging southeastward early this afternoon.
Water vapor imagery shows several vorticity maximums embedded
within the larger trough. At the surface, there is a 997 mb sfc
low over northern MN with a cold front trailing south from the
low across central IA. Guidance is in good agreement in driving
this upper trough into the western Great Lakes by Tuesday
morning, closing offs a deepening mid-upper level low with
multiple vorticity maximums pivoting around the mid-upper level
cyclone as it moves slowly eastward across the Great Lakes
through midweek.

Already seeing strong and gusty southerly winds today in
response to the tightening pressure gradient associated with the
sfc low over MN. The magnitude of the winds/gustiness should
ease a bit after sunset. The cold front will move quickly across
the area tonight, likely accompanied by a band of some rain,
especially north of I-80. The window of rain should be rather
short, likely lasting only an hour or so in any one given area.

Winds will shift to westerly in the wake of the front tonight,
but speeds and gusts will really begin to ramp up after sunrise
Tuesday. Deeply mixed boundary should allow for fairly frequent
gusts of 30-40 mph by late morning and especially during the
afternoon. There will probably be some sporadic gusts that tag
wind advisory criteria (45 mph gusts), but current thinking is
that any 45+ mph gusts will be much more the exception than the
rule, so not planning a wind advisory at this time.

Most guidance depicts one of the more vigorous vorts pivoting
around the upper low moving across our CWA during the morning
hours Tuesday. By the time the boundary layer becomes more
diurnally unstable, the better forcing with this vort should be
starting to push east of our area into MI and eastern IN. This
would suggest the better diurnal, afternoon cold core shower
chances may end up being just east of our CWA as inversion
heights lower some in wake of this vort. Forecast soundings
still depict convective cloud depths of 5-6kft, so certainly
plausible that there will be some isolated to scattered lighter
showers around in the afternoon, particularly northern CWA
closer to the core of the colder temps aloft. Shower chances
could linger into the early evening hours Tuesday, but should be
on the decrease after sunset Tuesday.

- Izzi

Wednesday through Monday:

The stacked deep upper and surface lows are progged to drift
east to the Lake Huron/Georgian Bay region on Wednesday, with our
area remaining in persistent blustery 15-20 mph (gusts 25-30 mph)
west-northwest low-level cold advection flow. This brisk west-
northwest flow regime will certainly keep robust lake effect
rain showers going into Thursday. However, the ~280-300 deg wind
direction will keep the focus primarily east/northeast of Porter
County Indiana. Temperatures again look to be limited to the low-
mid 50s, with 30s likely Wednesday night especially away from the
heart of the Chicago area. At this time, there appears to be
enough of a surface wind to prevent widespread frost conditions,
though clearing skies overnight could support stronger decoupling
than is currently depicted and will have to be monitored. With
this in mind, added in patchy frost mention into Thursday morning
for areas primarily west of the Fox River Valley.

Ensemble guidance is in reasonable agreement in gradually
shifting the long-wave upper trough off to the east of the
region Thursday into Friday, with an elongated northwest-
southeast oriented surface high pressure ridge spreading across
the area toward Friday morning. Light winds and clear skies
with the surface ridge overhead would potentially support a more
widespread frost/freeze threat (and associated headlines) late
Thursday night/early Friday morning. As such, introduced areas of
frost outside the heart of the Chicago urban heat island and away
from the lake in northwest Indiana.

Some modest moderation in temps is then indicated Friday into
the weekend, as ensembles shift the surface ridge off to our
east, and generally indicate some semblance of a short wave
tracking across the central/southern Plains. This wave is
progged to eventually get kicked into the Midwest/Great Lakes
region by another upstream long-wave trough moving onto the West
Coast. Most global ensembles increase precip chances into the
region in association with this scenario, though confidence in
placement and evolution of the leading Plains wave is fairly
low at this distance. Blended NBM pops in the 20-40 percent
range by Saturday into Sunday appear reasonable for now. Another
trough may eject into the region early next work week, which could
bring rain (and eventually even some thunder) chances back as
early as Monday afternoon and evening. As is typical at that range,
ensemble variance is quite large in the timing and evolution of
that possible synoptic system.

Castro/Ratzer

&&

.AVIATION /18Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 101 PM CDT Mon Oct 20 2025

Main Concerns:

- Gusty winds through most of the period: from the south today
  into this evening; a period of west-northwest tonight; and
  west/west-southwest later tonight through Tuesday

- A period of showers (with temporary MVFR CIGs/VSBY) tonight
  and then scattered showers on Tuesday

- Marginal LLWS this evening

Surface low pressure moving from northern Minnesota this
afternoon to the northern Great Lakes on Tuesday will affect
flying conditions, primarily in the form of strong winds. Nearly
due south winds this afternoon gusting to 25-30 kt will ease
some with sunset, at which point marginal LLWS criteria may be
met at the Chicago terminals into the mid to late evening.

A band of rain/showers associated with the system cold front
will quickly move across the area late this evening into the
overnight, likely bringing a period of MVFR flight category. In
addition, expect a brief wind shift to 280-300 deg with gusts in
the 25-30 kt range. Wind direction will settle back to west-
southwest after the rain ends. Scattered SHRA should develop by
the late morning as a strong disturbance moves overhead, though
with the more robust SHRA probably focusing to the east of the
TAF sites. Aside from the shower activity, strong westerly
(250-270 deg) winds will frequently gust to 30-35 kt,
occasionally to 35-40 kt through Tuesday afternoon.

Castro

&&

.MARINE...
Issued at 237 PM CDT Mon Oct 20 2025

Have issued a gale warning for this evening as strengthening low
level flow and neutral to slightly unstable conditions should
allow for some fairly regular southerly gale force gusts this
evening. Should see a break in the gales late tonight into early
Tuesday morning as wind shift to the west behind cold front. The
winds are then likely to ramp back up to 35-40kt westerly gusts
Tuesday afternoon, continuing Tuesday night, and likely into at
least early Wednesday morning. Model guidance does depict some
easing of the winds Tuesday night, but this corresponds to the
time of a significant increase in marine boundary layer
instability. This often results in winds over performing what
model guidance would suggest. Maintained 35kt gales Tuesday night,
but quite possible this could be too conservative, particularly
for the Indiana waters. Have issued a second gale warning for this
Tuesday afternoon through early Wednesday morning period.

- Izzi

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory until 6 PM CDT this evening for the IL
     and IN nearshore waters.

     Small Craft Advisory from 3 AM to noon CDT Tuesday for the IL
     and IN nearshore waters.

     Small Craft Advisory from 9 AM Wednesday to 1 AM CDT Thursday
     for Winthrop Harbor IL to Gary IN.

     Gale Warning from 6 PM this evening to 3 AM CDT Tuesday for
     the IL and IN nearshore waters.

     Gale Warning from noon Tuesday to 9 AM CDT Wednesday for the
     IL and IN nearshore waters.

     Small Craft Advisory from 9 AM Wednesday to 4 PM CDT Thursday
     for Gary to Burns Harbor IN-Burns Harbor to Michigan City
     IN.

&&

$$

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