Time zone · Americas
HST
Hawaii-Aleutian Standard Time
Hawaii-Aleutian Standard Time stretches from the tropical calm of Honolulu to the windswept Aleutian Islands, a region where most clocks stay fixed at UTC−10 but the far-western Aleutians spring forward to UTC−9 during daylight saving—so a single time zone quietly toggles between two offsets in step with the Alaskan coast.
Saturday, May 30, 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 Standard Time stretches from the tropical calm of Honolulu to the windswept Aleutian Islands, a region where most clocks stay fixed at UTC−10 but the far-western Aleutians spring forward to UTC−9 during daylight saving—so a single time zone quietly toggles between two offsets in step with the Alaskan coast.
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].
- Does all of Hawaii use daylight saving time?
- No. Hawaii as a whole stays on UTC−10 year-round; only the Aleutian portion of this region shifts to UTC−9 in summer.
- Which islands are covered by HST?
- The region includes Hawaii proper (Honolulu) and the Aleutian Islands west of 169°30′W (such as Adak).
- Why does Adak observe daylight saving?
- Adak follows the same cycle as Alaska’s Aleutian communities, moving clocks forward in spring and back in fall to align daylight hours.
- What’s unique about this time zone?
- It spans two member zones with different DST behavior: one springs forward, the other doesn’t, all under one region code.
- Is HST the same as Hawaiian time?
- Mostly—Hawaii itself never changes clocks, but the region label also covers the Aleutian summer shift to UTC−9.
- When does the DST switch happen?
- It follows the U.S. schedule, typically the second Sunday in March and the first Sunday in November.
- Does this region exist outside the United States?
- No. Both zones are located in the U.S., specifically Hawaii and the Alaska Aleutian chain.
- What’s a fun geographical quirk?
- From Honolulu to Adak, the zone spans tropical Pacific beaches to volcanic islands near the International Date Line bridge.
Free · Developer API
Time, as JSON.
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