Cold in Montana, December 26 to 31, 2021

Name: Cold in Montana, December 26 to 31, 2021
Start: 2021-12-26T00:45
End: 2021-12-31T23:59
Location: Montana

December 26 to 31, 2021 · NWS GGW · 11 events in 11 counties and zones

Where it happened

Every event with a place to put it; 11 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.

Tornadoes
Tropical storms and surge
Floods
Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

Open the live radar over this ground

The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 11

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

What happened

The episode as NWS GGW wrote it up.

A large arctic air mass descended southward from Canada to spread across our region for multiple days. Re-enforcing cold low pressure disturbances continued to rotate along the edge of this air mass, which supported this prolonged dangerously cold period. For most of these days, enough wind was present to create dangerously cold wind chill values for may locations across northeast Montana, and persisted through New Year's Eve.

What forecasters said that day

The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Glasgow, MT wrote its last area forecast discussion before the first event at Dec 25, 1:48 PM MST, 10 hours 57 minutes earlier.

Area forecast discussion, Dec 25, 1:48 PM MST, 10 hours 57 minutes before

Area Forecast Discussion
National Weather Service Glasgow MT
148 PM MST Sat Dec 25 2021

.DISCUSSION...

AFTERNOON UPDATE:
For this afternoon no big chanages were in store for the main
grids. What this has done is raise enough confidence in the short
term to go ahead and issue a Wind Chill Advisory across a large
chunk of the northern zones from 04Z tonight to 15Z Sunday
morning. Have cut off the Wind Chill at this point as Snow Totals
begin to ramp up across the west with the west to east passage of
a disturbance. Greater than 2 inches is expected for most of the
northern zones. Therefore, a Winter Weather Advisory was placed up
from here to 06Z Monday. There is room south of the Winter Wx
Advisory to add on further WindChill, but this may fluxuate a bit
and therefore will be allowing the next couple shifts a shot at
further refinement. This should also help with messaging by
keeping it simple for now. Afterward, Wind Chill Advisories and
Warnings will likely be permanant features through the end of the
7 day forecast with placement being the key future question. GAH

930AM UPDATE:
Most of the going forecast is on track. Will be releasing the Wind
Chill Advisory a bit early as most locations along the Milk and
Missouri Rivers no longer are in criteria or should exit within
the next hour. Radar echos hint that backside of the snow line is
beginning to pass through Malta and Jordan and appears to be on
track as well. The wind chill advisory will likely be returning
for this evening/overnight with the afternoon package, but will
also be struggling a bit with the confusing messaging as some
places will likely need a winter weather advisory by tomorrow that
could supercede wind chills later on, and then revert back to a
wind chill once any snow is over. GAH

MORNING DISCUSSION:
Very cold temperatures expected through the next week as an
arctic trof settles over central Canada and the northern plains.
Occasional snow is also possible over Montana with shortwaves
rounding the base of the cold trof.

Shortwave pushing through southern Montana this morning with a
band of snow lifting across northeast Montana. The increase in
clouds has moderated temperatures slightly but wind chill
advisory, although marginal, still seems reasonable. Light
accumulating snowfall will mostly last this morning with
accumulations around an inch.

A brief lull is expected this afternoon and evening, with the next
shortwave system moving through the region on Sunday. This system
is more robust, with higher snowfall amounts expected, especially
near the Canadian border.

Coldest air of the season will be drawn southward behind the
Sunday system, with temperatures expected to remain below zero for
much of the region through Wednesday night.

Arctic airmass begins to moderate for late in the week with upper
ridge moving into the northern Rockies. Beyond that broad outline,
ensemble spread and uncertainty is fairly high with regard to
temperatures as is usually the case when eroding a deep arctic
airmass.

&&

.AVIATION...

LAST UPDATED: 2000Z

FLIGHT CAT: MVFR-IFR

DISCUSSION: Back end of a snow line exists from KGGW to
KMLS westward as of 2000Z. Visibility will be the main
contributer to lowest flight category as snow passes through with
IFR. As the snow line exits the area MVFR ceilings will become the
next lowest contributer. MVFR Ceilings will likely hang till
about 09Z tonight when they may decrease down to IFR. VFR is not
expected for most terminals until about mid Sunday night.

WIND: East to northeast at 5 to 15 kts today through tonight.
Veering to the east Sunday and increasing to 10 to 20 kts.

GAH

&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 8 AM to 11 PM MST Sunday for
Central and Southeast Phillips...Central and Southern Valley...
Daniels...Eastern Roosevelt...Northern Phillips...Northern
Valley...Richland...Sheridan...Southwest Phillips...Western
Roosevelt.

Wind Chill Advisory from 9 PM this evening to 8 AM MST Sunday
for Central and Southeast Phillips...Central and Southern
Valley...Daniels...Eastern Roosevelt...Garfield...McCone...
Northern Phillips...Northern Valley...Richland...Sheridan...
Southwest Phillips...Western Roosevelt.

&&

weather.gov/glasgow

The radar

The national radar mosaic for the moment the first event began.

Open the radar archive at this moment

Event by event

11 cold/wind chill. Local standard time, as filed.

Cold/Wind Chill, Western Roosevelt

When: December 26, 12:45 AM MST to December 31, 11:59 PM MST
Where: Western Roosevelt forecast zone
Reported by: Department of Highways
Coordinates: 48.295, -105.016 (the zone’s center; the record gives no point)

For multiple sites across Western Roosevelt County, temperatures in the teens and 20s below zero and breezy winds created intermittent periods of wind chills of -40 or worse from early morning of the 26th into the late night of the 31st. The peak wind chill of -50 was recorded at 11:01 PM on the 29th at the McDonald's MT-13 DOT site (MTMCD).

Cold/Wind Chill, Central and Southern Valley

When: December 26, 9:20 PM MST to December 31, 3:40 PM MST
Where: Central and Southern Valley forecast zone
Reported by: RAWS
Coordinates: 48.365, -106.667 (the zone’s center; the record gives no point)

For multiple sites across Central and Southern Valley County, temperatures in the teens and 20s below zero and breezy winds created intermittent periods of wind chills of -40 or worse from late night of the 26th into the night of the 31st. The peak wind chill of -50 was recorded from 7:20 AM to 7:30 AM on the 27th at the Saint Marie MARCO site (07MT).

Cold/Wind Chill, Dawson

When: December 26, 11:03 PM MST to December 31, 11:59 PM MST
Where: Dawson forecast zone
Reported by: Department of Highways
Coordinates: 47.266, -104.899 (the zone’s center; the record gives no point)

At the Lindsay Divide DOT site (MTLND), temperatures in the teens and 20s below zero and breezy winds created intermittent periods of wind chills of -40 or worse from late night on the 26th into the late night of the 31st. The peak wind chill of -45 was recorded from 12:53 AM to 1:08 AM on the 27th.

Cold/Wind Chill, Wibaux

When: December 26, 11:08 PM MST to December 31, 9:55 PM MST
Where: Wibaux forecast zone
Reported by: ASOS
Coordinates: 46.965, -104.249 (the zone’s center; the record gives no point)

For multiple sites across and near Wibaux County, temperatures in the teens and 20s below zero and breezy winds created intermittent periods of wind chills of -40 or worse from late night on the 26th into the night of the 31st. The peak wind chill of -43 was recorded at 7:35 AM on the 27th at the Beach, ND ASOS site (K20U).

Cold/Wind Chill, Daniels

When: December 26, 11:35 PM MST to December 31, 11:59 PM MST
Where: Daniels forecast zone
Reported by: Department of Highways
Coordinates: 48.784, -105.549 (the zone’s center; the record gives no point)

For multiple sites across Daniels County, temperatures in the teens and 20s below zero and breezy winds created intermittent periods of wind chills of -40 or worse from late night of the 26th into the late night of the 31st. The peak wind chill of -52 was recorded at 5:13 AM on the 31st at the Navajo MT-5 DOT site (MTRED).

Cold/Wind Chill, McCone

When: December 27, 12:50 AM MST to December 31, 9:39 AM MST
Where: McCone forecast zone
Reported by: Department of Highways
Coordinates: 47.645, -105.795 (the zone’s center; the record gives no point)

For multiple sites across McCone County, temperatures in the teens and 20s below zero and breezy winds created intermittent periods of wind chills of -40 or worse from early morning of the 27th into the night of the 31st. The peak wind chill of -47 was recorded at 6:50 AM on the 27th at the Fort Peck Dam site (GGWFP).

Cold/Wind Chill, Sheridan

When: December 27, 1:01 AM MST to December 31, 11:59 PM MST
Where: Sheridan forecast zone
Reported by: Department of Highways
Coordinates: 48.721, -104.505 (the zone’s center; the record gives no point)

For multiple sites across Sheridan County, temperatures in the teens and 20s below zero and breezy winds created intermittent periods of wind chills of -40 or worse beginning as early as the morning of the 27th and lasting as long as the late night of the 31st. The peak wind chill of -53 was recorded at 9:34am on the 31st at the Comertown Turn-OFF MT-5 DOT site (MTCOM) as well as at 7:35pm on the 31st at the Sher-wood Airport (Plentywood) ASOS.

Cold/Wind Chill, Central and Se Phillips

When: December 27, 1:15 AM MST to December 31, 11:59 PM MST
Where: Central and Se Phillips forecast zone
Reported by: Department of Highways
Coordinates: 48.259, -107.913 (the zone’s center; the record gives no point)

For multiple sites across Central and Southeast Phillips County, temperatures in the teens and 20s below zero and breezy winds created intermittent periods of wind chills of -40 or worse from the early morning of the 27th into the late night of the 31st. The peak wind chill of -49 was recorded at 3:20 AM on the 28th at the Saco US-2 DOT site (MTSCO).

Cold/Wind Chill, Northern Valley

When: December 27, 3:44 AM MST to December 31, 10:44 PM MST
Where: Northern Valley forecast zone
Reported by: RAWS
Coordinates: 48.365, -106.667 (the zone’s center; the record gives no point)

At the Bluff Creek RAWS site (BLUM8), temperatures in the teens and 20s below zero and breezy winds created intermittent periods of wind chills of -40 or worse from the early morning of the 27th into the late night of the 31st. The peak wind chill of -45 was recorded at 7:44 AM on the 27th.

Cold/Wind Chill, Richland

When: December 27, 5:21 AM MST to December 31, 11:59 PM MST
Where: Richland forecast zone
Reported by: Mesonet
Coordinates: 47.788, -104.561 (the zone’s center; the record gives no point)

For multiple sites across Richland County, temperatures in the teens and 20s below zero and breezy winds created intermittent periods of wind chills of -40 or worse from early morning of the 27th into the late night of the 31st. The peak wind chill of -45 was recorded at 10:16 PM on the 31st at the Badger Creek CWOP Mesonet site (MTMCD).

Cold/Wind Chill, Eastern Roosevelt

When: December 27, 6:03 AM MST to December 31, 11:59 PM MST
Where: Eastern Roosevelt forecast zone
Reported by: Department of Highways
Coordinates: 48.295, -105.016 (the zone’s center; the record gives no point)

For multiple sites across Eastern Roosevelt County, temperatures in the teens and 20s below zero and breezy winds created intermittent periods of wind chills of -40 or worse from the morning of the 27th into the late night of the 31st. The peak wind chill of -44 was recorded at 9:53 PM on the 31st at the US-2 Stateline DOT site (MTSTA).

What these are

Cold/Wind Chill: Cold or wind chill below warning criteria that caused deaths, injuries or damage.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in Montana in 2021 Every state in 2021 This day in weather history Warnings in Montana, December 2021

Sources

NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 996480, 996479, 996586, 996594, 996476, 996481, 996477, 996478, 996475, 996582, 996577.