Current Time in MST Time Zone

Overview and Geographic Scope

MST (Mountain Standard Time) is used in parts of North America that remain on standard time year-round. Unlike many regions that shift to Mountain Daylight Time (MDT, UTC-06:00) in summer, MST keeps a constant UTC-07:00 offset. The primary areas using MST are in the state of Arizona (USA) and the state of Sonora (Mexico). In Arizona, most of the state observes MST all year, except the Navajo Nation which does observe DST. In Mexico, Sonora uses MST permanently. The IANA time zone database includes several zone names that share the same UTC-07:00 offset, but only a subset are fixed to MST without DST. The zones that are equivalent to MST (no DST) include: America/Phoenix (the canonical zone for Arizona), America/Hermosillo (Sonora), and America/Creston (a small area in British Columbia, Canada). Other zones like America/Denver use UTC-07:00 in winter but switch to UTC-06:00 in summer.

Offset and Abbreviation

The abbreviation MST stands for Mountain Standard Time. The offset is UTC-07:00, meaning MST is 7 hours behind Coordinated Universal Time. This offset is constant throughout the year because there is no daylight saving time adjustment. In regions that do observe DST, the same abbreviation MST is used only during the winter months; in summer they switch to MDT. But in MST-only zones, the abbreviation remains MST all year.

Daylight Saving Time Behavior

MST does not observe daylight saving time. This means clocks do not spring forward or fall back. The offset remains UTC-07:00 every day of the year. This is a deliberate choice, primarily to avoid the heat and energy consumption issues that shifting an hour would cause in hot desert climates like Arizona and Sonora. As a result, during the summer months, MST is effectively one hour behind the neighboring Mountain Time zones that do observe DST (e.g., Denver, Edmonton). In winter, MST aligns with those same zones.

Main Countries and Cities

The largest city in MST is Phoenix, Arizona, USA. Other major cities in MST include Tucson, Mesa, Chandler, and Scottsdale in Arizona, and Hermosillo and Ciudad Obregón in Sonora, Mexico. The zone also covers the entire state of Arizona (excluding the Navajo Nation) and the state of Sonora. In Canada, a small area around Creston, British Columbia, also uses MST year-round (America/Creston).

Business Hours and Scheduling

For scheduling calls, MST is often compared to US time zones. MST is 2 hours behind Eastern Time (ET) year-round. During US daylight saving time (mid-March to early November), MST is 1 hour behind Mountain Time (MT) zones that observe DST (e.g., Denver), and 2 hours behind Central Time (CT). In winter, MST aligns with Denver and other Mountain Time zones. For international calls, MST is 7 hours behind UTC, so noon in MST is 19:00 UTC. Common business hours (9 AM to 5 PM MST) correspond to 16:00 to 00:00 UTC. For calls to London (UTC+0/+1), MST is 7 or 8 hours behind; to Tokyo (UTC+9), MST is 16 hours behind; to Sydney (UTC+10/+11), MST is 17 or 18 hours behind.

Relationship to Other IANA Zones

The IANA database lists many zones at UTC-07:00. The ones that do not observe DST (i.e., permanent MST) are: America/Phoenix, America/Hermosillo, America/Creston. Zones that do observe DST (switching to MDT) include: America/Denver, America/Boise, America/Edmonton, America/Inuvik, and others. When using IANA identifiers, it is important to pick the correct zone: for Arizona (excluding Navajo) use America/Phoenix; for Sonora use America/Hermosillo; for Creston use America/Creston. For areas that observe DST, use the appropriate zone like America/Denver.