Time zone · Americas
HST
Hawaii-Aleutian Standard Time
Hawaii-Aleutian Time stretches across remote volcanic islands in the Pacific, blending Hawaiian island life with the rugged, windswept Aleutian chain off Alaska. It's a region where the clock itself seems split—Daylight Saving Time runs on Adak but not in Honolulu—making it one of the most rhythmically unique time patterns in the United States.
Friday, June 5, 2026
Current offset
UTC-10:00
Standard · HST
Daylight saving
Not observed
Year-round standard time
IANA zones
1
None observe daylight saving
DST offset
—
No summer variant
About HST
A fixed, year-round offset.
Hawaii-Aleutian Time stretches across remote volcanic islands in the Pacific, blending Hawaiian island life with the rugged, windswept Aleutian chain off Alaska. It's a region where the clock itself seems split—Daylight Saving Time runs on Adak but not in Honolulu—making it one of the most rhythmically unique time patterns in the United States.
IANA zones · the technical identifiers
The zone that resolve to HST.
For software, always store the IANA identifier — never the abbreviation alone. The database keeps these zones distinct because their rules can, and historically did, diverge.
Where HST is used
One country.
Same offset · UTC-10:00
Other zones at UTC-10:00 right now.
These named zones share HST's offset today. When daylight saving rules differ, they drift apart for part of the year.
Frequently asked questions
Common questions about HST, daylight saving, and how to handle it in software. Can't find what you need? Email [email protected].
- Why does only part of Hawaii-Aleutian Time observe Daylight Saving Time?
- Adak, in the Aleutian Islands of Alaska, follows DST along with most of the continental US, while Honolulu in Hawaii opts out. This split means the two zones that share the same base code live an hour apart for nearly half the year.
- Is Hawaii-Aleutian Standard Time the same as Hawaii Standard Time?
- Mostly, yes—Honolulu operates on HST year-round, which is UTC-10:00. However, during the DST months, Adak shifts to Aleutian Daylight Time (HDT), which is UTC-09:00, creating a one-hour difference between the two areas.
- What is the westernmost time zone in the United States?
- Adak, in the Aleutian Islands, is the westernmost inhabited US city and operates on HDT during DST and HST otherwise. This makes it one of the last places on Earth to see the New Year.
- How does living in Hawaii-Aleutian Time affect daily life?
- Residents often interact with both Hawaiian culture and Alaskan frontier spirit, depending on where they are. Communication with the mainland US can be tricky, as the time difference shifts with DST, requiring extra awareness for scheduling.
- Why is Aleutian Daylight Time (HDT) one of the rarest time zone abbreviations?
- HDT is only used in a tiny portion of the Aleutian Islands, making it one of the least commonly referenced time zone codes. Most world clocks and apps don't even display it as an option.
- How do people on Adak adjust when DST ends?
- On November 1, 2026, clocks on Adak will fall back from HDT (UTC-09:00) to HST (UTC-10:00), aligning with Honolulu for the winter months until DST begins again in March.
- Is there a big difference in sunrise and sunset times across this region?
- Yes—due to the vast longitudinal spread from Hawaii to Adak, sunrise and sunset times vary significantly, with Adak experiencing much longer summer days. During DST, Adak’s daylight hours can feel almost endless, closer to the Alaskan feel than Hawaiian tropics.
Free · Developer API
Time, as JSON.
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