Lewistown, Montana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

623
FXUS65 KTFX 071843
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1243 PM MDT Sun Jun 7 2026

.KEY MESSAGES...

 - Cold temperatures tonight, with a frost likely across Southwest
   Montana.

 - Dry and seasonably warm conditions Monday will be followed by
   another period of unsettled and cooler weather Tuesday through
   Thursday.

&&

.DISCUSSION...

 - Meteorological Overview:

Partial clearing tonight and lighter winds across southwest MT
will allow for efficient cooling and overnight low temps are
likely to reach the lower 30s there and mid 30s to around 40
across the plains where breezy winds will persist tonight.

Monday will be mainly dry with temperatures returning to seasonal
levels. An unseasonably strong upper level jet across the North
Pacific sends a series of shortwaves into the NW US within a
broad upper level trough that shifts across the Northern Rockies
and MT Tuesday through Thursday. This will bring daily chances for
showers and possibly some thunderstorms with temperatures again
trending below seasonal averages. Hoenisch


 - Forecast Confidence & Scenarios:

Cold Temperatures Tonight...

Breezy winds over the plains of Central and North Central Montana
are likely to help keep the boundary layer coupled to prevent
temperatures from falling too low tonight; however, there is a 30-
70% chance for temperatures to fall below 36 degrees (frost) along
and southwest of a Lewistown, to Great Falls, to Shelby line.
Additionally, there is a 5-15% chance that these areas could see
temperatures fall below 32 degrees. Further south within the valleys
of Southwest and Central Montana light winds throughout the night
and partial clearing will allow temperatures to fall lower than over
the plains. Here within the valleys there is generally a 30-80%
chance for lows to fall below 32 degrees and non-zero (i.e. less
than 5%) chance for lows to fall below 28 degrees with the exception
of the Big Hole Valley and West Yellowstone Area where there is a 30-
90% chance of a hard freeze (i.e. 28 degrees or colder). Those with
sensitive vegetation should take preventative measure to prevent
damage.

Strong Winds on Wednesday...

Climate anomaly indicators are pointing towards a potential wind
event during the middle of the upcoming work week, with ECMWF EFIs
supporting a climatologically unusual to very unusual wind event.
This is particularly true for areas along and north of the I-90
corridor where EFIs are in excess of 0.6, with values up to 0.75
along and west of the I-15 corridor and along the Montana Hwy 200/US
Hwy 87 corridor in Central Montana. NBM 5.0 probabilities for areas
north of the i-90 corridor have a 50% or greater chance for wind
gusts in excess of 40 mph, with a 20-50% chance for wind gusts in
excess of 50 mph across most locations. The exception for wind gusts
in excess of 50 mph are along and west of the I-15 corridor over the
plains and along the Montana Hwy 200/US Hwy 87 corridor in Central
Montana where probabilities are between a 70-80%, with a 20-30%
chance for gusts to exceed 60 mph in these areas. - Moldan

&&

.AVIATION...
07/18Z TAF Period

Showers and isolated thunderstorms will gradually exit to the east
through 00-06z Monday, with MVFR/low-VFR/VFR conditions improving
to VFR through this timeframe. As precipitation winds down
westerly winds will begin to increase, with strong and gusty winds
expected over the plains of Central and North Central Montana.
Winds will be strongest along and west of the I-15 corridor, with
the potential for mountain wave activity. Mountains will remain
obscured through the early evening hours. - Moldan

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  36  71  48  69 /  10   0   0  30
CTB  35  67  44  65 /  10   0   0  20
HLN  34  71  49  68 /  10   0  10  80
BZN  30  71  47  67 /  30   0  20  90
WYS  26  64  37  54 /   0   0  50 100
DLN  31  70  46  65 /  10   0  20  90
HVR  37  73  47  74 /  20   0   0  20
LWT  32  69  45  68 /  20   0   0  70

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
None.
&&

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