Mountain Standard Time is 7 hours behind Coordinated Universal Time (UTC).
Mountain Daylight Time is 6 hours behind UTC.
In locations observing Daylight Saving Time (DST) during part of the year, Mountain Time is not static but switches between MDT and MST.
Where and when is Mountain Time observed?
- Arizona - Navajo Nation only
- Idaho - most of the state except western counties
Benewah, Bonner, Boundary, Clearwater, Kootenai, Latah, Lewis, Nez Perce, Shoshone and north part of Idaho
- Kansas - some western counties only
Greeley, Hamilton, Sherman and Wallace
- Nebraska - western counties
Arthur, Banner, Box Butte, Chase, Cheyenne, Dawes, Deuel, Dundy, Garden, Grant, Hooker, Keith, Kimball, Morrill, Perkins, Scotts Bluff, Sheridan, and Sioux and the western part of Cherry
- New Mexico
- North Dakota - South-Western parts
counties of Adams, Billings, Bowman, Golden Valley, Grant, Hettinger, Mercer, Slope and Stark, and southern parts of Dunn and McKenzie, most of Morton and Sioux counties
- Oregon - parts of Malheur county only
- South Dakota - western counties
Bennett, Butte, Corson, Custer, Dewey, Fall River, Haakon, Harding, Jackson, Lawrence, Meade, Pennington, Perkins, Shannon, and Ziebach, and the western parts of Stanley
- Texas - a few counties in west
El Paso and Hudspeth and part of Culberson
- British Columbia - a few eastern communities
Cranbrook, Golden, Invermere
- Northwest Territories
- Nunavut - Kugluktuk, Cambridge Bay only (Other parts use EST/EDT or EST only)
- Saskatchewan - only Lloydminster
- Baja California Sur
MST all year round
Some locations, such as the ones below don't switch and are in MST all year long.