MST time now (Mountain Standard Time)

What MST means

MST stands for Mountain Standard Time, UTC−7. It is used in the US and Canadian Rocky Mountain states and provinces, Arizona and Sonora.

It is a standard (winter) time. Places on MST that observe daylight saving time switch to MDT (UTC−6) in summer, so MST is a fixed offset while the local clock is not.

Who is on Mountain Standard Time all year

MST is UTC−7. Denver, Salt Lake City and Calgary’s old zone use it in winter and switch to MDT (UTC−6) in summer. Arizona, except the Navajo Nation, never switches, so Phoenix shows MST all year (NIST lists most of Arizona among the places without daylight saving time). Since 2020 Yukon and since 2026 British Columbia also keep UTC−7 permanently, and tzdata calls that MST.

Alberta also kept its summer clock: it moved to permanent UTC−6 on June 18, 2026, which tzdata labels CST from November 1, 2026. In winter Calgary is therefore an hour ahead of Denver and on the same time as Chicago.

Where and when MST is used

8 zones use MST all year. 4 zones use it for part of the year only, switching to daylight saving time in the other months. Computed from tzdata under the current rules.

How long MST has been used

In the tzdata record, Denver has used MST since 1883, Phoenix has used MST since 1883 and Cambridge Bay has used MST since 1920.

MST in the past

Zones whose tzdata history shows MST before 2025 but that no longer use it:

• America/Edmonton (Calgary): 1906–2024
• America/Inuvik (Inuvik): 1979–2024
• America/Chihuahua (Chihuahua): 1922–2022
• America/Ojinaga (Ojinaga): 1922–2022
• America/North_Dakota/Beulah (Beulah): 1883–2010
• America/Bahia_Banderas (Bahia Banderas): 1922–2010
• America/North_Dakota/New_Salem (New Salem): 1883–2003
• America/North_Dakota/Center (Center): 1883–1992
• America/Swift_Current (Swift Current): 1905–1972
• America/Regina (Saskatoon): 1905–1960
• America/Mexico_City (Mexico City): 1922–1932
• America/Monterrey (Monterrey): 1922–1932

MST converted to other zones

Every column is a fixed offset, so this table is valid on any date. Remember that the regions behind some columns switch to summer time (EST to EDT, CET to CEST, GMT to BST); the clock in those cities is then an hour later than the column.

Related zones and conversions

• MDT time
• America/Denver time zone
• UTC−7 time
• MST to EST
• Time zones of the world
• Daylight saving time
• Time zone converter