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| Hawaii–Aleutian Time Zone | |
|---|---|
| Time zone | |
 | |
| UTC offset | |
| HST | UTC−10:00 |
| HDT | UTC−09:00 |
| Current time | |
| 12:11, 25 October 2025HST[refresh] 13:11, 25 October 2025HDT[refresh] | |
| Observance ofDST | |
| DST is observed in some of this time zone. | |
TheHawaii–Aleutian Time Zone observes Hawaii–Aleutian Standard Time (HST)[1][2] by subtracting ten hours fromCoordinated Universal Time (UTC−10:00). The clock time in this zone is based on themean solar time of the150th meridian west of theGreenwich Observatory.
The zone takes its name from the two areas it includes:Hawaii and the portion ofAlaska'sAleutian Islands west of 169° 30′ W longitude.
Duringdaylight saving time (DST), the Alaskan portion observes Hawaii–Aleutian Daylight Time (HDT,UTC−09:00), while Hawaii stays on standard time. Hawaii has not observed daylight saving time since September 1945.[3]
Until 1947,UTC−10:30 was used asstandard time in Hawaii. On June 8 of that year, a new territorial law moved Hawaiian Standard Time 30 minutes ahead.[4]
Hawaii–Aleutian Standard Time[5] was established to maintain consistency in the scheduling of business and government activities across Hawaii and the Aleutian Islands.
French Polynesia uses UTC−10:00 for its major cities.[6] TheCook Islands also use the same time.[7] These areas do not use DST. "Hawaii–Aleutian Time Zone" is a U.S. term and for that reason the Polynesian areas are not considered to be a part of the Hawaii–Aleutian Time Zone.
The largest city and metropolitan area in the Hawaii–Aleutian Time Zone areHonolulu and its metropolitan area, respectively.
Time zones §9.47. The following forms are to be used when abbreviating names of time zones: ... HDT—Hawaii-Aleutian daylight time (not observed in HI) ... HST—Hawaii-Aleutian standard time
Hawaii-Aleutian (HT); HST -10; HDT -9; DST observed in Aleutian Islands, but not Hawaii
