820
FXUS65 KBYZ 061222
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
622 AM MDT Mon Oct 6 2025

.KEY MESSAGES...

- Chilly with localized fog early this morning.

- Building high pressure aloft brings dry and warmer weather
  through Friday.

- Next reasonable chance of precipitation is the weekend.

&&

.DISCUSSION...
Today through Tuesday Night...

Upper trof dropping slowly thru WY continues to bring some very
light precip to our south as of 07z, mainly over the Bighorns, but
some light showers may eke into far southern Powder River/Carter
before it exits entirely. Once we get past ~15z, dry conditions
will persist through the remainder of the period as high pressure
builds over the region. There is a low risk (20%) of localized
valley fog early this morning. Existing cloud cover is preventing
temps from dropping too quickly but skies are mostly clear in the
far east, and we are starting to see breaks along portions of the
western foothills. Dew point spreads are quite low at this hour
(4F or less) so fully expect there to be some fog by sunrise.
Something to monitor.

07z temperatures are in the 30s to lower 40s. Again depending on
cloud cover, a good portion of the region should be in frost or
freeze territory by daybreak. For many locations this will be the
chilliest morning seen so far this fall, which says more about the
warm early fall than the coolness of this air mass.

Expect high temperatures in the 50s today and 60s Tuesday as the
ridge brings persistent downslope warming. Frost and freeze
potential will be more localized tonight due the downslope
gradients and warm advection. Lows will reach the upper 20s to
lower 40s, coolest in sheltered valleys. Tuesday night will be
milder yet.

When skies clear be sure to check out the snow-topped mountains.

JKL

Wednesday through Monday...

There is now good agreement that the cutoff upper level low
pressure system off the west coast will lead to increased heights
across Montana. This will create temperatures around 5 degrees
above average Wednesday and Thursday (70 F) before increasing to 5
to 15 degrees above average Friday and Saturday (70-80 F).

There is good ensemble agreement that an upper level trough will
drop into the region next weekend and bring a pattern change to
wetter and cooler conditions. Precipitation chances return
Saturday and last through Monday. Currently, the NBM is giving a
30-70% chance for getting greater than 0.25 inches of
precipitation across the region. Given how far out this system is,
it is difficult to provide further details at this time. Torgerson

.AVIATION...

Area of light rain in the far southeast corner of MT will
dissipate by ~15z. Localized fog and low stratus will produce
MVFR-IFR early this morning, and fog is being reported at
Harlowton as of 12z, but the chance of fog impacting a TAF site is
quite low (10%). The risk of fog will end by 15z. Expect a
transition to widespread VFR by late morning. This afternoon
through tonight will see VFR and mostly clear skies as high
pressure aloft builds over the region. JKL

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Tue     Wed     Thu     Fri     Sat     Sun
-------------------------------------------------------
BIL 058 040/066 044/072 043/070 043/076 052/076 044/058
    0/U 00/U    00/U    00/U    00/U    13/W    55/W
LVM 056 029/066 033/070 036/071 038/075 044/070 034/053
    0/U 00/U    00/U    00/U    01/U    35/W    66/W
HDN 058 031/067 034/073 036/071 040/077 046/079 042/060
    0/U 00/U    00/U    00/U    00/U    12/W    54/W
MLS 059 034/067 039/073 040/072 042/079 050/080 045/060
    0/U 00/U    00/U    00/U    00/U    01/U    43/W
4BQ 056 034/065 040/070 041/071 044/078 054/080 045/060
    0/B 00/U    00/U    00/U    00/U    01/U    33/W
BHK 059 031/066 037/073 040/071 040/074 049/080 041/061
    0/U 00/U    00/U    00/U    00/U    00/U    32/W
SHR 056 028/066 031/071 036/071 039/079 046/078 037/059
    1/B 00/U    00/U    00/U    00/U    12/W    44/W

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.

&&

$$
weather.gov/billings