Current Time in HDT (Hawaii-Aleutian Daylight Time)
About HDT
The daylight saving time for the Aleutian Islands west of -169.5° longitude. Hawaii itself does not observe daylight saving time. HDT is one hour ahead of Hawaii-Aleutian Standard Time (HST). Active from March to November.
UTC Offset: -09:00
Current time shown is based on the representative IANA zone: America/Adak
Hawaii-Aleutian Daylight Time (HDT)
Hawaii-Aleutian Daylight Time (HDT) is a daylight saving time zone used during the summer months in a small part of the United States. It is 9 hours behind Coordinated Universal Time (UTC-09:00). HDT is the daylight saving variant of Hawaii-Aleutian Standard Time (HST, UTC-10:00), meaning clocks spring forward one hour in the spring and fall back in the autumn.
What is Hawaii-Aleutian Daylight Time?
HDT stands for Hawaii-Aleutian Daylight Time. It is observed only during daylight saving time (DST), which typically runs from the second Sunday in March to the first Sunday in November in the United States. During the rest of the year, the region uses Hawaii-Aleutian Standard Time (HST, UTC-10:00). The offset of HDT is UTC-09:00, placing it one hour ahead of HST.
Where is HDT Observed?
HDT is observed exclusively in the Aleutian Islands of Alaska, which are part of the United States. The IANA time zone database includes the following identifiers for this zone: America/Adak, America/Atka, and US/Aleutian. The primary city in this zone is Adak, Alaska. Note that the rest of Alaska uses Alaska Time (AKST/AKDT), and the state of Hawaii does not observe daylight saving time at all, remaining on HST year-round. Therefore, HDT applies only to the Aleutian Islands west of 169°30′ W longitude.
Neighboring Time Zones
HDT (UTC-09:00) is bordered by several other zones. To the east, the rest of Alaska uses Alaska Daylight Time (AKDT, UTC-08:00) during summer, which is one hour ahead of HDT. To the west, across the International Date Line, the nearest zone is Kamchatka Time (PETT, UTC+12:00), which is 21 hours ahead of HDT. To the south, Hawaii (HST, UTC-10:00) does not observe DST, so during summer, HDT is one hour ahead of Hawaii. When DST ends, HST and HST (in Hawaii) are both at UTC-10:00, so the Aleutians and Hawaii share the same time during winter.
Business Hours Guidance
When scheduling calls or meetings with locations on HDT, keep in mind that it is only active during the summer months. During DST, HDT is 9 hours behind UTC. For example, 9:00 AM HDT is 6:00 PM UTC, 2:00 PM Eastern Daylight Time (EDT), and 11:00 AM Alaska Daylight Time (AKDT). Because the Aleutian Islands are sparsely populated, most business interactions with the region occur during standard time (HST) or with other Alaskan zones. If you need to reach someone in Adak, the best window is typically 8:00 AM to 5:00 PM HDT, which corresponds to 5:00 PM to 2:00 AM UTC (the next day).
Key Facts
- Abbreviation: HDT (Hawaii-Aleutian Daylight Time)
- UTC Offset: UTC-09:00
- Standard Time Counterpart: Hawaii-Aleutian Standard Time (HST, UTC-10:00)
- Observing Region: Aleutian Islands, Alaska, United States (west of 169°30′ W)
- IANA Zones: America/Adak, America/Atka, US/Aleutian
- DST Period: Second Sunday in March to first Sunday in November (U.S. rules)
Frequently Asked Questions
Does Hawaii observe Hawaii-Aleutian Daylight Time?
No. Hawaii does not observe daylight saving time. Hawaii remains on Hawaii-Aleutian Standard Time (HST, UTC-10:00) year-round. HDT is only used in the Aleutian Islands of Alaska.
What is the difference between HDT and HST?
HDT (UTC-09:00) is one hour ahead of HST (UTC-10:00). HDT is used during daylight saving time, while HST is used during the rest of the year.
Which major cities use HDT?
The only significant settlement in the HDT zone is Adak, Alaska, which is the largest city in the Aleutian Islands west of 169°30′ W. Other small communities include Atka and Shemya.
When does HDT start and end?
HDT begins on the second Sunday in March at 2:00 AM HST, when clocks spring forward to 3:00 AM HDT. It ends on the first Sunday in November at 2:00 AM HDT, when clocks fall back to 1:00 AM HST.
How is HDT different from Alaska Daylight Time (AKDT)?
AKDT (UTC-08:00) is one hour ahead of HDT (UTC-09:00). AKDT covers most of Alaska, while HDT is limited to the western Aleutian Islands. During standard time, the Aleutians use HST (UTC-10:00) while the rest of Alaska uses AKST (UTC-09:00).
What is the UTC offset for HDT?
Hawaii-Aleutian Daylight Time is UTC-09:00.