Lewistown, Montana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

025
FXUS65 KTFX 252329
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
529 PM MDT Sat Jul 25 2026

Aviation Section Updated.

.KEY MESSAGES...

 - Dangerously hot temperatures continue through the weekend,
   with heat peaking on today.
 - Isolated thunderstorms today are expected across Central
   Montana, some of which may produce strong outflow winds and
   very little rainfall.
 - Heat lessens slightly next week, but temperatures still remain
   warm.

&&

.DISCUSSION...
/Issued 201 PM MDT Sat Jul 25 2026/

 - Meteorological Overview:

Upper level ridging will continue to be the dominant weather
feature of our weather over the upcoming week, keeping us
generally warm and dry save for a few opportunities for afternoon
thunderstorms. Heat will continue to be the most widespread hazard
through the weekend as the ridge remains positioned in a way that
keeps us in southwesterly flow aloft. This heat will peak on
today, even as a shortwave moving over Washington will kick off a
few afternoon showers and thunderstorms. More details on the heat
and thunderstorms can be found below in the Confidence and
Scenarios sections.

Temperatures will lessen slightly Sunday as the ridge wanes
slightly, but temperatures will remain hot with most lower
elevations reaching the mid 90s to near 100. Temperatures will
wane slightly further Monday as the ridge continues to wane a bit,
but by Monday the ridge will settle into a state it will more or
less maintain its strength through the remainder of the week. The
main day to day difference will be a few rounds of monsoonal
moisture working through the area, which may allow for afternoon
thunderstorms to pop up. As of now, the best chances for afternoon
thunderstorms outside of today will be after Wednesday, but I
would not rule out a storm popping up any day over the next week.

 - Forecast Confidence & Scenarios:

Heat through Sunday: The ongoing heat wave will continue through
Sunday as the upper level ridge maintains its strength. The main
question will be just how hot does it get during the day, and to
what degree does it cool off overnight. Raw model output seems to
be fairly consistent at keeping lower elevation locations across
the plains near 100-107today, and upper 90s to near 100 on Sunday.
However, there are a few areas of uncertainty. While smoke
remains a source of some uncertainty, the impact from the smoke
appears to have been rather muted the past 24 hours or so. The
other, more significant wild card for today will be afternoon
convection, which would quickly cool off any areas that see
thunderstorms and/or their outflows, which may keep them from
reaching their true temperature potential provided the storms move
through before mid to late afternoon.

Thunderstorms today: Convective models continue to show a robust
round of showers and thunderstorms across Southwestern and Central
Montana this afternoon and evening. While an area of light
showers/thunderstorms did manage to move through Jefferson,
Broadwater, and Meagher Counties, satellite shows that a more
robust area of convective initiation appears to be underway across
Southwestern Montana and Eastern Idaho as of 1PM. Given the very
warm and dry environment, any thunderstorm is liable to produce
little rainfall on the ground, and may also produce strong
outflows. Storms will also have just enough shear to get
organized, and dry air aloft may help promote processes that
produce downburst winds and their associated outflows. Ludwig


&&

.AVIATION...
26/00Z TAF Period

Showers and thunderstorms capable of strong and erratic wind gusts
will continue to progress northeastward across Central and Southwest
Montana, finally exiting or diminishing after 04Z. Another round of
showers and thunderstorms develops again Sunday afternoon, mostly
across Southwest Montana. -AM

&&

.FIRE WEATHER...

A Red Flag Warning remains in effect across portions of North-
Central Montana today with widespread minimum RH values below
20%, frequent gusts up to 30 to 40 mph, and hot temperatures
expected. Additionally, isolated thunderstorms may produce
localized strong wind gusts and cloud to ground lightning, along
with very little rainfall. The concern will be that any fire that
starts may be very difficult to contain. Those who are doing
anything that could generate sparks, including yard work, farming,
towing trailers, or other activities should do everything
possible to prevent a spark while traveling and/or recreating
outdoors.

Marginal to elevated fire weather concerns may extend into Sunday
and Monday as well, though lesser wind speeds and lower
temperatures give lower confidence for critical fire weather
conditions at the moment. Ludwig/Wilson

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  61  97  60  94 /  20   0   0   0
CTB  59  89  55  89 /   0   0   0   0
HLN  60  95  60  93 /  30   0  10   0
BZN  61  95  58  94 /  40  10  20  10
WYS  50  87  50  86 /  20  20  10  10
DLN  56  91  55  90 /  30  20  10   0
HVR  63  98  60  97 /  30   0   0   0
LWT  60  94  58  91 /  40   0  10   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 9 PM MDT this evening for Central and
Eastern Lewis and Clark National Forest Areas-Chouteau and
Fergus Counties-Eastern Glacier/Toole/Central/Eastern
Pondera/Liberty-Hill and Blaine Counties-Lewis and Clark
National Forest Rocky Mountain District-Rocky Mountain Front.

Heat Advisory until 9 PM MDT Sunday for Beaverhead and Western
Madison below 6000ft-Canyon Ferry Area-Eastern Glacier, Western
Toole, and Central Pondera-Eastern Pondera and Eastern Teton-
Eastern Toole and Liberty-Gallatin Valley-Gates of the Mountains-
Helena Valley-Madison River Valley-Meagher County Valleys-
Missouri Headwaters.

Extreme Heat Warning until 9 PM MDT Sunday for Bears Paw
Mountains and Southern Blaine-Fergus County below 4500ft.

Heat Advisory from midnight tonight to 9 PM MDT Sunday for
Cascade County below 5000ft-Hill County-Judith Basin County and
Judith Gap-Northern Blaine County-Western and Central Chouteau
County.

Extreme Heat Warning until midnight MDT tonight for Cascade
County below 5000ft-Hill County-Judith Basin County and Judith
Gap-Northern Blaine County-Western and Central Chouteau County.

&&

$$
http://www.weather.gov/greatfalls