Arctic air behind a cold front pushed into eastern Montana, bringing very cold temperatures on the morning of the 10th. Although winds were relatively light, they were strong enough in combination with the bitter cold temperatures to create extreme wind chills across much of the area. Wind chills of 40 below zero or worse were common, with the lowest wind chill value of 58 below zero in Phillips County.

Extreme Cold/Wind Chill in WESTERN ROOSEVELT, MONTANA
From 09-FEB-18 22:13:00 to 10-FEB-18 04:18:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Wind chills at the Poplar AWOS dropped under 40 below at approximately 10:15 PM on the 9th, and stayed near or below that point until approximately 6:30 on the morning of the 10th. The McDonalds Montana Department of Transportation site recorded wind chills under 40 below from approximately midnight on the morning of the 10th to 4:30 on the morning of the 10th.

Extreme Cold/Wind Chill in GARFIELD, MONTANA
From 09-FEB-18 23:48:00 to 10-FEB-18 04:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Temperatures across Garfield County dropped into the 20s and 30s below zero on the night of the 9th and the early morning of the 10th. Even with winds ranging from calm to 10 miles per hour, wind chills periodically dropped to 40 below zero or less between just before midnight on the 9th and approximately 4:00 on the morning of the 10th.

Extreme Cold/Wind Chill in DAWSON, MONTANA
From 10-FEB-18 03:56:00 to 10-FEB-18 07:56:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Temperatures in the teens and 20s below and relatively light winds combined to produce bitterly cold wind chill values at Glendive early in the morning of the 10th.

Extreme Cold/Wind Chill in RICHLAND, MONTANA
From 09-FEB-18 21:15:00 to 09-FEB-18 21:15:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

A wind chill value of 40 below zero was recorded at the Sioux Pass Montana Department of Transportation site.

Extreme Cold/Wind Chill in MCCONE, MONTANA
From 10-FEB-18 06:38:00 to 10-FEB-18 06:38:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

The Montana Department of Transportation site recorded a wind chill value of 41 below zero at 6:38 AM on the 10th.

Extreme Cold/Wind Chill in CENTRAL AND SE PHILLIPS, MONTANA
From 09-FEB-18 18:35:00 to 10-FEB-18 11:55:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Observations at the Malta Airport AWOS site showed wind chill values less than 40 below zero from 6:35 PM the evening of the 9th through 11:55 AM the morning of the 10th. The lowest wind chill value was 58 below zero, occurring from 5:15 AM through 8:15 AM the morning of the 10th.

Extreme Cold/Wind Chill in CENTRAL AND SOUTHERN VALLEY, MONTANA
From 09-FEB-18 20:53:00 to 09-FEB-18 20:53:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Temperatures in the 20s below zero and fairly light winds combined to produce bitterly cold wind chills across the area. A 40 below zero wind chill value was recorded by the Glasgow airport ASOS at 8:53 PM on the evening of the 9th.