Lewistown, Montana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

148
FXUS65 KTFX 260604
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1204 AM MDT Sun Jul 26 2026

.KEY MESSAGES...

 - Dangerously hot temperatures continue through today.

 - Heat lessens slightly Monday through Thursday, but
   temperatures still remain warm and in the 90s.

&&

.DISCUSSION...

 - Meteorological Overview:

Upper level ridging will dominate over the Northern Rockies
throughout the entire period; however, with the ridge axis being
orientated just to the east and over the Northern High Plains, which
would place Southwest through North Central Montana beneath overall
southwest flow aloft, isolated showers and thunderstorms can`t be
ruled out from the afternoon through evening hours on any given day.
This is especially true considering the fact that monsoonal moisture
will continue to lift north and east within the ridge over the
timeframe, with subtle waves providing additional forcing
occasionaly. High temperatures will remain well above normal through
the day today, with temperatures only cooling several degrees from
Monday through Thursday but still remaining above normal. By Friday
strong warm air advection and increasing 1000-500mb thicknesses will
help to push temperatures back near the century mark across most
lower elevations, with these hot temperatures persisting into the
upcoming work week. - Moldan

 - Forecast Confidence & Scenarios:

Heat Advisories and Extreme Heat Warnings through this Evening...

Hot temperatures will linger across much of Southwest through North
Central Montana through the day today, with eastern areas of Central
and North Central Montana (areas along and east of a Havre to
Lewistown line) seeing a warm start to the day as temperatures only
fall into the low 70s early this morning. Increasing wildfire smoke
from regional wildfires will continue overspreading the Northern
Rockies through the day as the upper level flow remains out of the
southwest, with the thickest smoke expected to be over Central and
North Central Montana. Should this smoke be thicker than currently
expected then it is possible that high temperatures along and north
of the Montana Hwy 200 corridor could be some 5 to 10 degrees too
warm for the day on Sunday. Should temperatures be inhibited from
warming to the current forecasted highs then an earlier ending to
the current suite of Heat Advisories or Extreme Heat Warnings would
be warranted.

Return of Extreme Temperatures by Friday...

While temperatures will remain hot through the upcoming work week,
latest climate anomaly indicators are suggesting the potential for
another unusual period of hot temperatures beginning on Friday and
extending into the upcoming weekend; most notably across Southwest
Montana. NBM5.0 probabilities for high temperatures of 100 degrees or
warmer range from a 20-60% chance along and north of the I-90
corridor on Friday for lower elevations, with probabilities
increasing to a 40-80% chance on Saturday for these same locations.
The fact that the climate anomaly indicators are suggesting another
unusual period of hot temperatures is remarkable considering that
July 30 through August 1st is the climatological peak for average
high temperatures across Southwest through North Central Montana. -
Moldan

&&

.AVIATION...
26/06Z TAF Period

Other than passing cirrus clouds, mostly clear skies will be
persistent through the TAF period across North-Central MT. There
is a low chance for isolated showers to linger overnight across
Southwest MT. Another round of isolated showers and thunderstorms
to develop Sunday afternoon and evening for areas mainly along
and south of I-90. Gusty winds will be possible with
thunderstorms. Breezy synoptic winds develop along the North-
Central MT plains Sunday afternoon. Smoke aloft can cause
slantwise visibility issues through the TAF period. -Wilson

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  97  60  95  59 /   0   0   0   0
CTB  88  54  89  55 /   0   0   0   0
HLN  95  60  94  60 /   0   0   0   0
BZN  95  59  95  58 /  30  20  10  20
WYS  86  52  86  49 /  30  20  20   0
DLN  92  56  91  55 /  20  10   0   0
HVR  98  59  97  59 /   0   0   0   0
LWT  94  58  92  58 /   0  10   0  10

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 9 PM MDT this evening for Beaverhead and
Western Madison below 6000ft-Canyon Ferry Area-Cascade County
below 5000ft-Eastern Glacier, Western Toole, and Central Pondera-
Eastern Pondera and Eastern Teton-Eastern Toole and Liberty-
Gallatin Valley-Gates of the Mountains-Helena Valley-Hill County-
Judith Basin County and Judith Gap-Madison River Valley-Meagher
County Valleys-Missouri Headwaters-Northern Blaine County-
Western and Central Chouteau County.

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

&&

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