Idaho real estate glossary

Understanding Time Zones in Idaho: MST vs. MDT

Mountain Standard Time (MST) and Mountain Daylight Time (MDT) represent the two time offsets used in most of Idaho depending on the time of year. While the region transitions between these two, understanding the split within the state is essential for those relocating or coordinating travel within Idaho.

Updated with grounded research as of 2026-11-09.

The short answer

The primary difference between Mountain Standard Time (MST) and Mountain Daylight Time (MDT) is the time offset from Coordinated Universal Time (UTC) caused by the observance of Daylight Saving Time (DST). MST is UTC-7 and is used during the winter months, while MDT is UTC-6 and is used during the warmer months when clocks are set forward one hour.

Key facts

Mountain Standard Time (MST) Offset
UTC-7
Mountain Daylight Time (MDT) Offset
UTC-6
Idaho Geographic Time Split
Most of Idaho operates on Mountain Time, while the northern panhandle (north of the Salmon River) operates on Pacific Time.

Standard Time vs. Daylight Saving Time

In Idaho, the shift between MST and MDT is governed by the observance of Daylight Saving Time. During the late autumn and winter months, the state reverts to Standard Time (MST). As spring approaches, the state "springs forward" one hour to adopt Daylight Time (MDT), allowing for more daylight hours during the evening.

  • MST (Mountain Standard Time): UTC-7; observed in winter.
  • MDT (Mountain Daylight Time): UTC-6; observed in spring, summer, and early autumn.

Idaho's Unique Time Zone Geography

It is critical to note that not all of Idaho follows the Mountain Time Zone. Per Idaho Code § 67-120, the state is split geographically. Areas north of the Salmon River fall into the Pacific Time Zone, observing Pacific Standard Time (PST) and Pacific Daylight Time (PDT). This can create confusion for those traveling between the northern panhandle and the southern regions of the state.

  • Southern/Central/Eastern Idaho: Mountain Time (MST/MDT).
  • Northern Idaho: Pacific Time (PST/PDT).

Planning Considerations for Relocation

When moving to or working in Idaho, ensure your scheduling tools are set to the correct region. Virtual meetings, delivery deadlines, and construction schedules often span both time zones within the state. Always confirm whether a location is north or south of the Salmon River to avoid missing appointments or miscalculating delivery times.

Common questions

When does Idaho switch between MST and MDT?

Idaho follows the federal schedule for Daylight Saving Time. Clocks typically shift forward to MDT on the second Sunday in March and shift back to MST on the first Sunday in November.

Why does Idaho have two different time zones?

The split at the Salmon River is a historical and geographic designation intended to align northern Idaho communities more closely with the Pacific Northwest region, primarily Washington and Oregon, for economic and logistical reasons.

Does all of Idaho change its clocks?

Yes, both the Mountain Time Zone and the Pacific Time Zone regions in Idaho observe Daylight Saving Time, meaning the entire state transitions between standard and daylight time twice annually.

Related Idaho questions

  • Which Idaho counties are in the Pacific Time Zone?
  • What are the exact boundaries of the Salmon River time split?
  • How does the time difference affect commuting between Idaho regions?

Sources and verification