We've started the work week off on a quiet and warm note with above average highs ranging from the mid 40s to mid 50s. The exception to the quiet conditions will be for portions of central and north central Montana where breezy, downsloping winds are likely.
Overnight, expect partly cloudy skies with lows in the mid 20s to mid 30s and another warm day for Tuesday.
Starting Tuesday evening, though, changes begin to move in! Isolated rain and snow are likely to develop overnight Tuesday and into Wednesday (most impacts in southwest Montana) with highs now in the mid 30s. A Winter Weather Advisory is in place for Gallatin & Madison Counties from 5pm Tuesday - 11pm Wednesday for mainly the higher terrain (Raynolds, Bozeman and Targhee Passes). 3" to 5" will be likely with isolated amounts up to 7". Winds could gust as high as 35 mph.
As that system moves out by Thursday, colder air will begin to enter the region with gusty winds at first. The cold front will move in from the north with light snow possible by Thursday evening. Most snow will fall in the mountains, but lower elevations could pick up a quick inch or two. Snowfall is expected to end by early Saturday morning. Highs Thursday will be in the mid 30s and in the 20s to low 30s for Friday.
At this point, temperatures are looking to be quite cold for the weekend ahead, but the greatest uncertainty is with just how cold it might get. Snow cover from any snowfall this week, cloud cover & winds will all play a significant role. The important thing to note is that it's going to get really cold regardless!
The weekend looks dry with a mix of clouds and sun. After morning lows in the single digits both above and below zero, highs will top out in the teens to low 20s on Saturday. Sunday morning lows look to remain above zero in the single digits with daytime highs in the upper 20s to low 30s.