A significant weather shift is arriving in Western Montana and North-Central Idaho Saturday evening through Monday morning, September 12-14, bringing widespread rain to the valleys and snow to the high terrain. Snow accumulations are possible above 6,000 feet, particularly on Sunday. Anyone heading into the backcountry should prepare for a legitimate hypothermia risk due to the sudden onset of cold, wet, and raw conditions. High temperatures will take a hit, dropping 15 to 20 degrees below normal by Sunday. Also, expect morning fog and low clouds to start your days.