Current Time in UTC-10 Zone
About UTC-10
Discover all countries and IANA time zones in the UTC-10 offset. View the current local time for all locations with this UTC offset.
UTC Offset: UTC-10
What is UTC-10?
UTC-10 is a fixed offset from Coordinated Universal Time: clocks on this offset are always 10 hours behind UTC. Unlike a named time zone, a UTC offset never shifts for daylight saving time. Regions that observe DST alternate between two different UTC offsets across the year, which is why the countries listed below can change with the seasons.
In aviation, shipping, and military usage, UTC-10 corresponds to the Whiskey time zone (W), written with the letter suffix W in Zulu notation. Pilots and NATO forces use these letter zones so an order like "0800W" is unambiguous worldwide.
UTC-10 vs GMT-10
On a wall clock, UTC-10 and GMT-10 show the same time. The difference is in what they refer to: UTC is the modern standard kept by atomic clocks and used in computing, aviation, and science, while GMT is the older convention based on mean solar time at Greenwich. Technical systems, logs, and APIs should reference UTC-10.
Time & Daylight in UTC-10
Time Difference Between UTC-10 and Major Cities
Live local time and the difference from UTC-10 right now.
Current time shown is based on the representative IANA zone: America/Adak
UTC-10: The Hawaii-Aleutian and French Polynesia Time Offset
UTC-10 is a fixed time offset that places clocks 10 hours behind Coordinated Universal Time. Unlike named time zones such as Hawaii-Aleutian Standard Time (HST) or Tahiti Time (TAHT), UTC-10 is a pure offset that does not change for daylight saving time. However, some regions that use this offset during standard time shift to UTC-9 in summer, meaning the list of territories at UTC-10 is not constant year-round. This article explores the unique characteristics of UTC-10, its major regions and cities, and practical scheduling considerations.
Fixed Offset vs. Named Time Zone
A fixed UTC offset, such as UTC-10, is simply a number indicating how many hours to subtract from UTC to get local time. It never changes. A named time zone, like Pacific/Honolulu, may include rules for daylight saving time (DST) or historical shifts. For example, Hawaii-Aleutian Standard Time (HST) is UTC-10 during standard time, but the Aleutian Islands (America/Adak) observe DST and move to UTC-9 in summer. Thus, while UTC-10 is static, the list of places that observe it at any given moment is dynamic.
Regions and Cities at UTC-10
Several territories and cities use UTC-10 as their standard offset year-round or seasonally. The following are the primary regions and representative cities:
- United States (Hawaii and Aleutian Islands): Honolulu (Pacific/Honolulu) and Adak (America/Adak) are key cities. Hawaii stays on UTC-10 all year, while the Aleutian Islands (west of 169°30' W) shift to UTC-9 for DST.
- Cook Islands: Rarotonga (Pacific/Rarotonga) uses UTC-10 year-round, with no DST.
- French Polynesia: Tahiti (Pacific/Tahiti) and surrounding islands use UTC-10 year-round, also without DST.
Other IANA zones at this offset include US/Hawaii (an alias for Pacific/Honolulu) and Pacific/Johnston (though Johnston Atoll is uninhabited).
DST and Seasonal Changes
Because UTC-10 is a fixed offset, regions that observe DST move away from it for part of the year. Specifically, the Aleutian Islands (America/Adak) spring forward to UTC-9 (UTC-9) on the second Sunday of March and fall back to UTC-10 on the first Sunday of November. Hawaii, Cook Islands, and French Polynesia do not observe DST, so they remain at UTC-10 year-round. This means that during summer, the only inhabited places at UTC-10 are Hawaii, Cook Islands, and French Polynesia, while the Aleutians are at UTC-9.
Military and Zulu Time Notation
In military and aviation timekeeping, UTC-10 is designated by the letter 'W' (Whiskey). Zulu time (Z) is the military name for UTC. Note that UTC and GMT are functionally identical for everyday clock reading, though GMT is a time zone while UTC is a standard. On a clock, both show the same time.
Practical Scheduling Notes
When scheduling across UTC-10 regions, be aware of DST differences. For example, during summer, Honolulu (HST, UTC-10) is 1 hour behind Adak (HDT, UTC-9). Also, note that the International Date Line lies just west of the Cook Islands and French Polynesia, making them among the last places to see each day. For conference calls, typical business hours in Honolulu (9 AM to 5 PM HST) correspond to 7 PM to 3 AM UTC, and 9 AM to 5 PM in Tahiti is 7 PM to 3 AM UTC.
Key Facts About UTC-10
- UTC-10 is 10 hours behind UTC, equivalent to 10 hours behind GMT.
- It is used in the Pacific Ocean, spanning from Hawaii to French Polynesia.
- No country uses UTC-10 as its sole time zone year-round; the Aleutian Islands leave it for DST.
- The offset is sometimes called Hawaii-Aleutian Standard Time (HST) or Tahiti Time (TAHT), but these names imply DST rules.
Frequently Asked Questions
What is the difference between UTC-10 and HST?
UTC-10 is a fixed offset that never changes. HST (Hawaii-Aleutian Standard Time) is a named time zone that is UTC-10 during standard time, but the Aleutian Islands observe DST and shift to UTC-9 in summer. Hawaii itself stays on UTC-10 all year, so for Hawaii, HST and UTC-10 are the same year-round.
Does any part of the United States use UTC-10 year-round?
Yes, the state of Hawaii uses UTC-10 year-round. The Aleutian Islands (west of 169°30' W) use UTC-10 only during standard time (winter) and switch to UTC-9 for daylight saving time.
What is the military letter for UTC-10?
The military letter for UTC-10 is 'W' (Whiskey). Zulu time (Z) is used for UTC.
Which countries are always at UTC-10?
No country is entirely at UTC-10 year-round. The Cook Islands and French Polynesia (overseas collectivity of France) use UTC-10 year-round, but they are not sovereign countries. The United States has Hawaii at UTC-10 year-round, but the Aleutian Islands shift for DST.
What is the time difference between UTC-10 and UTC?
UTC-10 is 10 hours behind UTC. For example, when it is 12:00 UTC, it is 02:00 in UTC-10.
Is UTC-10 the same as GMT-10?
Yes, for practical purposes, UTC and GMT are interchangeable. So UTC-10 is the same as GMT-10 on a clock.