The National Weather Service has issued a Wind Chill Advisory for all of north-central and northeast Montana through Tuesday.
This means frigid air will combine with brisk winds to push wind chill values down to dangerously low levels.
Actual temperatures on Tuesday morning dipped to -25 in some areas.
Anyone venturing outdoors should cover all exposed skin and dress accordingly to prevent frostbite and hypothermia, which can occur within 30 minutes of exposure.
Wind chills of -15 to -35° are likely through early Wednesday morning, especially along the Hi-Line and across northeast Montana.
High temperatures will be in the single digits for most areas for the rest of the week.
More snow is expected to fall across parts of Montana this week.
STORMTracker meteorologist Mike Rawlins says the frigid air will remain in place near the ground, while abundant moisture streams in above it.
This will result in widespread snow across the Treasure State, beginning on Wednesday and wrapping up on Saturday.
Rawlins says some places could receive more than a foot of snow during the 4-day period.
Drivers should be prepared for difficult driving conditions with snow-covered, icy roads.
The Montana Department of Transportation has several tools to track road conditions: