Mountain Time Zone (MST/MDT)
Complete guide to Mountain Standard Time and Mountain Daylight Time
Convert Mountain Time to Another Timezone
About Mountain Time Zone
The Mountain Time Zone (MT) is one of the four main time zones in the continental United States. It covers the Rocky Mountain region and nearby areas, including major cities like Denver, Phoenix, Salt Lake City, and Albuquerque. Mountain Time is 2 hours behind Eastern Time and 1 hour ahead of Pacific Time.
Mountain Standard Time (MST)
Mountain Standard Time (MST) is observed during the winter months and is 7 hours behind Coordinated Universal Time (UTC-7). MST runs from the first Sunday in November at 2:00 AM until the second Sunday in March at 2:00 AM. Arizona observes MST year-round without changing clocks.
Mountain Daylight Time (MDT)
Mountain Daylight Time (MDT) is observed during the summer months and is 6 hours behind Coordinated Universal Time (UTC-6). When clocks "spring forward" on the second Sunday in March, most of Mountain Time switches from MST to MDT. The zone returns to MST on the first Sunday in November when clocks "fall back."
Daylight Saving Time Schedule
- Spring Forward: Second Sunday in March at 2:00 AM → clocks move to 3:00 AM MDT (except Arizona)
- Fall Back: First Sunday in November at 2:00 AM → clocks move back to 1:00 AM MST (except Arizona)
- Duration: MDT is observed for approximately 8 months per year in most areas
- Arizona Exception: Arizona stays on MST year-round (except Navajo Nation)
Major Cities in Mountain Time Zone
The Mountain Time Zone includes cities across the Rocky Mountain region:
| United States | Canada & Mexico |
|---|---|
| Denver, CO | Calgary, AB |
| Phoenix, AZ | Edmonton, AB |
| Salt Lake City, UT | Chihuahua, MX |
| Albuquerque, NM | |
| Tucson, AZ | |
| Colorado Springs, CO | |
| Boise, ID | |
| El Paso, TX |
States in Mountain Time Zone
The following US states observe Mountain Time for all or part of their territory:
- Entirely in MT: Colorado, Montana, New Mexico, Utah, Wyoming
- Partially in MT: Arizona (entire state on permanent MST), Idaho (southern portion), Kansas (westernmost counties), Nebraska (western portion), Nevada (part of West Wendover area), North Dakota (southwestern counties), Oregon (most of Malheur County), South Dakota (western portion), Texas (El Paso and Hudspeth counties)
Arizona's Unique Timezone Situation
Arizona is unique among US states in that most of the state does not observe daylight saving time. Arizona remains on Mountain Standard Time (MST, UTC-7) year-round. The exception is the Navajo Nation, which spans into multiple states and does observe MDT to maintain consistency across its territory. During summer months when other Mountain Time areas use MDT, Arizona is effectively on the same time as Pacific Daylight Time.
Business and Industry
Mountain Time serves several important industries:
- Energy & Mining: Significant oil, gas, and mineral extraction operations
- Tourism & Recreation: Major ski resorts and national parks
- Technology: Growing tech hubs in Denver, Salt Lake City, and Phoenix
- Standard Business Hours: 9:00 AM - 5:00 PM MT
Other Contiguous US Time Zones
Explore the other major US time zones:
Frequently Asked Questions
What is Mountain Time Zone?
Mountain Time Zone is one of the four main US time zones. It uses Mountain Standard Time (MST, UTC-7) in winter and Mountain Daylight Time (MDT, UTC-6) in summer. It covers the Rocky Mountain region including Denver, Phoenix, and Salt Lake City.
Does Arizona observe Mountain Time?
Arizona observes Mountain Standard Time (MST, UTC-7) year-round and does not change clocks for daylight saving time. The exception is the Navajo Nation, which does observe MDT. During summer, Arizona is effectively on the same time as Pacific Daylight Time.
What is the current time in MST?
Mountain Time currently observes either MST (UTC-7) from November to March, or MDT (UTC-6) from March to November in most areas. Arizona remains on MST year-round. Check the live clock at the top of this page for current Mountain Time.
When does MST change to MDT?
MST changes to MDT on the second Sunday in March at 2:00 AM, when clocks spring forward to 3:00 AM. MDT changes back to MST on the first Sunday in November at 2:00 AM, when clocks fall back to 1:00 AM. Arizona does not participate in these changes.
What is the difference between MST and MDT?
MST (Mountain Standard Time) is UTC-7 and is used during winter months. MDT (Mountain Daylight Time) is UTC-6 and is used during summer months. The difference is 1 hour, with MDT being one hour ahead of MST.
Why doesn't Arizona change time?
Arizona chose not to observe daylight saving time primarily due to the hot climate. The extra hour of evening daylight would mean higher air conditioning costs and more energy consumption. The state has remained on permanent MST (with the exception of the Navajo Nation) since 1968.
What time zone is Denver in?
Denver, Colorado is in the Mountain Time Zone. It observes MST (UTC-7) during winter months and MDT (UTC-6) during summer months. Denver follows standard daylight saving time transitions.
Is Utah in Mountain Time?
Yes, all of Utah is in the Mountain Time Zone. Salt Lake City and all other Utah cities observe MST in winter and MDT in summer, following standard daylight saving time transitions.
How many hours behind EST is MST?
Mountain Time is always 2 hours behind Eastern Time, year-round. When it's 12:00 PM EST/EDT, it's 10:00 AM MST/MDT. This difference remains constant because both zones change their clocks for DST on the same dates (except Arizona).
What states are entirely in Mountain Time?
States entirely in the Mountain Time Zone include Colorado, Montana, New Mexico, Utah, and Wyoming. Arizona is also entirely in the timezone but uniquely stays on MST year-round without observing daylight saving time.