Frost Advisory 2, NWS Missoula, MT

542 
WWUS75 KMSO 161431
NPWMSO

URGENT - WEATHER MESSAGE
National Weather Service Missoula MT
831 AM MDT Sat May 16 2026

MTZ003-005-171445-
/O.NEW.KMSO.FR.Y.0003.260518T0200Z-260518T1500Z/
/O.EXT.KMSO.FR.Y.0002.260517T0200Z-260517T1500Z/
Flathead/Mission Valleys-Missoula/Bitterroot Valleys-
831 AM MDT Sat May 16 2026

...FROST ADVISORY IN EFFECT FROM 8 PM SUNDAY TO 9 AM MDT MONDAY...
...FROST ADVISORY NOW IN EFFECT FROM 8 PM THIS EVENING TO 9 AM MDT
SUNDAY...

* WHAT...For the first Frost Advisory, temperatures as low as 32 will
  result in frost formation. For the second Frost Advisory,
  temperatures as low as 30 will result in frost formation.

* WHERE...Flathead/Mission Valleys and Missoula/Bitterroot Valleys.

* WHEN...For the first Frost Advisory, from 8 PM this evening to 9 AM
  MDT Sunday. For the second Frost Advisory, from 8 PM Sunday to 9 AM
  MDT Monday.

* IMPACTS...Frost could harm sensitive outdoor vegetation.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold.

&&

$$

417 
WWUS75 KMSO 171504
NPWMSO

URGENT - WEATHER MESSAGE
National Weather Service Missoula MT
904 AM MDT Sun May 17 2026

MTZ003-005-181500-
/O.EXP.KMSO.FR.Y.0002.000000T0000Z-260517T1500Z/
/O.CON.KMSO.FR.Y.0003.260518T0200Z-260518T1500Z/
Flathead/Mission Valleys-Missoula/Bitterroot Valleys-
904 AM MDT Sun May 17 2026

...FROST ADVISORY REMAINS IN EFFECT FROM 8 PM THIS EVENING TO 9 AM
MDT MONDAY...

* WHAT...Temperatures as low as 29 will result in frost formation.

* WHERE...Flathead/Mission Valleys and Missoula/Bitterroot Valleys.

* WHEN...From 8 PM this evening to 9 AM MDT Monday.

* IMPACTS...Frost could harm sensitive outdoor vegetation. Sensitive
  outdoor plants may be killed if left uncovered.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold.

&&

$$

Area Forecast Discussion
National Weather Service Missoula MT
122 AM MDT Sat May 16 2026

.DISCUSSION...

KEY MESSAGES:

- Unsettled, cool, and showery conditions persist into the
  weekend.

- Mountain snow this weekend will create difficult conditions for
  backcountry recreation, especially along the Continental
  Divide.

- Widespread frost and freezing temperatures are highly likely
  Sunday through Tuesday mornings.

At 1am, the snow level remains between 5500-6000 feet, we do
expect them to lower over the weekend eventually to 4000 feet or
lower. What does this mean, well the potential for a slushy
accumulation during hours of darkness at mountain pass level and
higher. Sun angles and lack of moderate precipitation intensities
will keep any impacts during the day to people ill- prepared for
cool and wet conditions. Those that are recreating in the
mountains should plan for cool and showery conditions, that can
produce hypothermia if lacking preparation. Showers will continue
through the weekend under cyclonic flow, mainly in the mountains
with light precipitation amounts, except along the ID/MT border,
Mission Mountains, and Glacier National Park Region where 0.50 to
1.00 inch of water equivalent is possible by Sunday evening. That
same time frame and those mountains ranges will also have the
potential for 4 to 12 inches of snow, mainly above 5000 feet.
Higher valleys of southwest MT could receive 1 to 5 inches of
snow, mainly tonight through Sunday morning.

Note: those forecast snow amounts are for a period of time longer
than our current winter weather advisories, hence the differences
in amounts.

By Monday, temperatures will be 5-10 degrees below normal for
this time of year. Kids will need jackets for the morning bus and
be carrying them home during the afternoon. Sensitive vegetation
will need care both Monday and Tuesday mornings, as temperatures
lower into the 20s in western Montana and higher valleys of north-
central ID. Cloud cover over the weekend, will likely keep
overnight lows above freezing below 4000 feet.

Tuesday through Friday will see a warming trend with dry
conditions. By Friday, temperatures could be 5-8 degrees warmer
than normal as a chance for showers returns.

&&

.AVIATION... Widespread showers have arrived, favoring KGPI,
KMSO, and KHRF. Expect widespread lowered ceilings down to about
2500 feet by Saturday morning, as well as continued precipitation
through about midday transitioning to scattered showers and
thunderstorms in the afternoon. Precipitation will obscure terrain
throughout the Northern Rockies airspace.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Winter Weather Advisory from midnight Saturday night to midnight
     MDT Sunday night for Bitterroot/Sapphire Mountains...
     Butte/Blackfoot Region...Potomac/Seeley Lake Region...West
     Glacier Region.

ID...None.
&&