A Dense Fog Advisory is in effect until noon MDT Monday for eight zones in southwest Montana, including Bozeman, Dillon and West Yellowstone.
Visibility will vary and could drop to a quarter mile or less in dense fog.
NWS Great Falls issued the advisory at 1:05 p.m. MDT Sunday.
Patchy fog is expected to become more widespread and dense tonight into Monday morning.
Where the Advisory Applies
Valleys: Gallatin Valley, Madison River Valley, Canyon Ferry Area and Missouri Headwaters.
Southwest Montana: Northwest Beaverhead County, and Beaverhead and Western Madison below 6,000 feet.
Mountains: Elkhorn and Boulder Mountains, and the Gallatin and Madison County Mountains and Centennial Mountains.
Cities and passes include Bozeman, Big Sky, West Yellowstone, Three Forks, Townsend, Boulder, Whitehall, Dillon, Ennis, Wisdom, Chief Joseph Pass, Elk Park Pass, Big Hole Pass, Raynolds Pass, Homestake Pass and Targhee Pass.
Driving Hazards
Low visibility could make driving conditions hazardous.
Frost deposition may make roads slippery, especially over bridges.
NWS Great Falls says fog is a concern along the divide, in southwest Montana and in parts of the plains.
Early Sunday, patchy dense fog developed around Bozeman, West Yellowstone and Wisdom, with visibility below one half mile in some areas.
Snow Moves In Monday Night
A Pacific weather system will bring light snow Monday night into Tuesday.
Accumulating snow will mostly stay in the mountains, especially along the divide and over southwest Montana.
Plan for variable road conditions, particularly over the passes.
Read full article: Dangerous Dense Fog Advisory Issued for 5 Counties in Montana as Visibility Drops
The post “Dangerous Dense Fog Advisory Issued for 5 Counties in Montana as Visibility Drops” by Luka Trcek was published on 10/25/2026 by www.travelinglifestyle.net