Snow will develop in Fergus and Judith Basin Counties. It will be on the lighter side with 1-3 inches expected at lower elevations, higher amounts possible for passes. A few snow showers could work into eastern Cascade county but Great Falls should stay primarily dry tonight.
Monday night: Temperatures will fall through midnight into the low to mid teens before staying steady there through daybreak. A spot snow shower is possible in Great Falls, with steady snow off to the east.
Tuesday: A warm front moves through which allows out temperatures to jump up into the low to mid 40s. High pressure develops behind the front and ushers in mostly sunny skies region-wide. However, the wind will pick up for the afternoon and evening with gusts up to 40mph possible. Clouds increase a bit overnight giving us mild overnight lows in the mid to upper 30s.
Wednesday: Mostly sunny to partly cloudy skies and mild temperatures. Highs in the low to mid 40s. Breezy conditions persist with gusts up to 40mph likely. Overnight lows will be in the mid to upper 20s. Partly cloudy skies overnight.
Thursday: Clouds will increase throughout the day ahead of a cold front that moves in late in the day. Temperatures top out around 40 degrees ahead of the front. A few snow showers are possible associated with the cold front, especially for Helena. Winds will also increase briefly as the front passes, with gusts up to 45mph possible. Temperatures crash behind it. Overnight lows will be in the low to mid teens.
Christmas Eve: Temperatures will start out in the upper teens and low 20s but crashing throughout the day. By dinnertime, most areas will be in the single digits. Mostly cloudy skies expected. Overnight lows fall to -5 to -10 degrees with wind chills as low as -20 to -25 degrees. A few snow showers are possible in the Rockies and south of Great Falls. Heavy mountain snow is possible in western Montana Christmas eve-Christmas day.
Christmas Day: Single digits to around 10 degrees. A mix of sun and clouds. A few snow showers are possible, especially in the mountains. Temperatures fall to -10 to -20 Christmas night as skies begin to clear.
Sunday: Coldest air of the season thus far with highs on either side of 0 degrees. Subzero wind chills likely throughout the day. Mix of sun and clouds with scattered snow showers also possible.
Monday: Scattered snow showers with continued frigid temperatures. Highs will be between 0 and 10 degrees across the area with wind chills below zero throughout the day.