A re-enforcing cold air mass from southern Saskatchewan swept across the international border into northeast Montana. The associated gusty winds from the west and northwest dropped wind chill values below -40 for some locations north of US Highway 2 and east of MT Highway 24.
Every event with a place to put it; 5 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
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.
The episode as NWS GGW wrote it up.
A re-enforcing cold air mass from southern Saskatchewan swept across the international border into northeast Montana. The associated gusty winds from the west and northwest dropped wind chill values below -40 for some locations north of US Highway 2 and east of MT Highway 24.
The national radar mosaic for the moment the first event began.
5 cold/wind chill. Local standard time, as filed.
At the McDonalds MT-13 DOT site (MTMCD), temperatures of -12 to -16 combined with wind speeds of 11 to 32 mph to create wind chill values of near -40 to -43 for more than 10 hours from the night of the 17 through the early morning of the 18th.
At the Saint Marie MARCO mesonet site (07MT), temperatures of -12 to -16 combined with wind speeds of 12 to 30 mph to create wind chill values of near -40 to -43 for more than 11 hours from the late night of the 17th through most of the morning of the 18th.
At the Navajo MT-5 DOT site (MTRED), temperatures of -12 to -16 combined with wind speeds of 19 to 41 mph to create wind chill values of -40 to -48 for 11 and 1/2 hours from the late night of the 17th through the morning of the 18th.
At the Comertown Turn-Off MT-5 DOT site (MTCOM), temperatures of -12 to -16 combined with wind speeds of 15 to 42 mph to create wind chill values of -40 to -48 for almost 11 hours from the late night of the 17th through the morning of the 18th. In addition, at the Crosby RAWS site (CSBN8), temperatures of -12 to -16 combined with wind speeds of 17 to 32 mph to create wind chill values of -40 to -42 for about 7 hours through most of the morning of the 18th.
At the US-2 @Stateline DOT site (MTSTA), temperatures of -13 to -15 combined with wind speeds of 13 to 27 mph to create wind chill values of near -40 to -41 for more than 5 hours on the morning of the 18th.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2020Every state in 2020This day in weather historyWarnings in Montana, January 2020
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 2026-10-01. Each event’s entry at NCEI: 875373, 875375, 875374, 875377, 875376.