DeKalb, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

564
FXUS63 KLOT 061729
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
1229 PM CDT Tue Oct 6 2026

.KEY MESSAGES...

- Near to above normal temperatures with predominantly dry
  conditions are expected through much of this week.

&&

.DISCUSSION...
Issued at 111 AM CDT Tue Oct 6 2026

Winds will turn southwesterly with increasing breezes into the
afternoon as a fast-moving shortwave zips across southern
Ontario. Forecast soundings suggest some occasional 25-30 mph
gusts will be possible this afternoon, particularly across far
northern Illinois/close to the Wisconsin state line. Dewpoint/RH
trends remain a bit tricky as a plume of very dry 850-700 mb air
will meander across the forecast area today. Diurnal mixing is
progged to be deepest across our south, and have lowered
dewpoints towards 40 based on the better performing guidance of
late which results in min RH values either side of 30 percent,
with higher values closer to the WI/IL state line. Winds look
light enough within the driest airmass to preclude an elevated
fire danger at this point.

An attendant cold front will approach the region late tonight.
Ahead of the northwest wind shift, it`s not out the question
some shallow mist/fog develops across far northwest Illinois
prior to daybreak. Coverage and magnitude of any BR looks too
low to include in the grids at this time, however. In the wake
of the front, modest cold advection will drive northwesterly
breezes across the region through Wednesday morning and
afternoon. Still fairly deep mixing should allow temperatures to
climb back into the 70s, and perhaps near 80 in our far south.

High pressure returns with a modest cool down on Thursday before
strengthening southwesterlies drive a warming trend into the
weekend. Robust warm advection will develop Friday night into
Saturday and some guidance (GFS) continues to squeeze out a
little light precipitation. Associated soundings don`t look
overly supportive of this, however, and sub-mentionable PoPs
from the NBM seem appropriate at this time.

Saturday looks dry, warm, and breezy, with highs potentially
making a run into the lower 80s south of about I-80 (and mid-
upper 70s elsewhere). There is some uncertainty by Sunday
regarding the proximity of an area of rain associated with
tropical moisture/remnants interacting with a broad upper low
pushing out of the ArkLaMiss. The extended multi-model consensus
continues to suggest that this activity will remain off to our
south and east, and given the expansiveness and magnitude of the
dry airmass overhead, will continue to show precip-free
conditions in the area. Assuming precip and clouds remain
shunted to our southeast, Sunday will be another warm day with
highs in the upper 70s and lower 80s even up to the lake.

Shortwave ridging is forecast to build to our south early next
week, and we`ll remain on its northern fringes. While this may
open us up to some low precip chances, most activity currently
looks like it`ll remain displaced just to our north.

Carlaw

&&

.AVIATION /18Z TAFS THROUGH 00Z THURSDAY/...
Issued at 1229 PM CDT Tue Oct 6 2026

The only minor aviation forecast concerns are with breezy
southwest winds this afternoon, and a marginal LLWS setup
overnight.

Surface high pressure continues to drift off to the east of the
region at midday, while a cold front approaches slowly from the
northwest across MN. In between these features, a tightening
surface pressure gradient will result in southwest winds
becoming increasingly breezy, gusting near 25 kts during the
mid-late afternoon hours. Surface winds will decrease with the
approach of sunset early this evening, while a 35-40 kt low-
level jet develops aloft. With surface winds likely remaining in
the 6-10 kt range overnight, this will set up only marginal
LLWS conditions and have not included in the TAFs. The peak
low-level jet speeds (near 40 kts) would be in the 02-08Z time
frame. Surface winds will eventually shift northwest near 10 kt
Wednesday morning, as the surface cold front moves through the
area.

Otherwise, the air mass remains quite dry across the region and
only some patchy VFR cloud cover is expected through the period.

Ratzer

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory until 7 PM CDT this evening for the IL
     nearshore waters.

&&

$$

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