Time zone · Americas
MDT
Mountain Daylight Time
Mountain Daylight Time (MDT, UTC-06:00) is the summer clock of the Rockies, from the United States into western Canada and northern Mexico. Denver, Boise, Cambridge Bay, and Ciudad Juárez spring forward to it from the second Sunday in March to the first Sunday in November, trading the crisp, early mountain darkness for longer golden evenings, while Alberta and the Northwest Territories stopped changing clocks in 2026 and stay on UTC-06:00 all year.
Wednesday, October 14, 2026
Current offset
UTC-06:00
Daylight · MDT
Daylight saving
Active
Reverts 1 Nov 2026
IANA zones
6
4 observe DST, 2 don't
DST offset
—
No summer variant
About MDT
Standard time, with a summer shift.
Mountain Daylight Time (MDT, UTC-06:00) is the summer clock of the Rockies, from the United States into western Canada and northern Mexico. Denver, Boise, Cambridge Bay, and Ciudad Juárez spring forward to it from the second Sunday in March to the first Sunday in November, trading the crisp, early mountain darkness for longer golden evenings, while Alberta and the Northwest Territories stopped changing clocks in 2026 and stay on UTC-06:00 all year.
IANA zones · the technical identifiers
The 6 zones that resolve to MDT.
For software, always store the IANA identifier — never the abbreviation alone. The database keeps these zones distinct because their rules can, and historically did, diverge.
Cities across MDT
Local time, city by city.
6 cities
Where MDT is used
3 countries.
Same offset · UTC-06:00
Other zones at UTC-06:00 right now.
These named zones share MDT's offset today. When daylight saving rules differ, they drift apart for part of the year.
Convert
MDT to the world's clocks.
Frequently asked questions
Common questions about MDT, daylight saving, and how to handle it in software. Can't find what you need? Email [email protected].
- Why does Mountain Daylight Time apply to places in three different countries?
- Mountain Daylight Time covers parts of the United States, Canada, and Mexico because all three nations share the same longitudinal band across the Rocky Mountains. Cities like Denver, Edmonton, and Ciudad Juárez all fall within the same UTC-6 offset during the summer months.
- How does daylight saving time affect daily life in the Mountain region?
- When clocks spring forward, cities like Boise and Denver gain an extra hour of evening sunlight, which residents take advantage of for hiking, outdoor dining, and other mountain activities before the short winter days return.
- Why was UTC-06:00 chosen for Mountain Daylight Time?
- Mountain Standard Time (UTC-07:00) roughly matches mean solar time around 105°W, the longitude of the Rockies. Mountain Daylight Time moves the clock one hour ahead of that for summer, shifting daylight into the evening.
- How does Mountain Daylight Time compare to Pacific Daylight Time?
- Mountain Daylight Time is one hour ahead of Pacific Daylight Time (PDT). When it's noon in Los Angeles, it's already 1 PM in Boise and Denver, giving mountain states a head start on the day's business.
- When does Mountain Standard Time resume?
- On the first Sunday of November, Denver, Boise, Cambridge Bay, and Ciudad Juárez fall back from MDT to Mountain Standard Time (MST, UTC-07:00). Alberta and the Northwest Territories stopped changing clocks in 2026 and stay on UTC-06:00.
- Are there any major cities in the Mountain Time Zone?
- Ciudad Juárez, Mexico, and Denver, Colorado, are the largest cities that switch to MDT each summer. Phoenix stays on UTC-07:00 all year, and Calgary and Edmonton stay on UTC-06:00 all year.
Source: IANA tzdb2026d · Reviewed
Free · Developer API
This time zone, as JSON.
Its defining offset, DST status and member counts, from one endpoint.
Also in the API: time zones by coordinates, conversions that flag daylight saving gaps, and abbreviations decoded.
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