Hawaii–Aleutian Time Zone
The Hawaii–Aleutian Time Zone observes Hawaii–Aleutian Standard Time (HST) by subtracting ten hours from Coordinated Universal Time (UTC−10:00). The clock time in this zone is based on the mean solar time of the 150th meridian west of the Greenwich Observatory.
During daylight 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.
French Polynesia uses UTC−10:00 for its major cities. The Cook Islands also use the same time. 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 in the Hawaii–Aleutian Time Zone is Honolulu; the Honolulu Metropolitan Area is the largest metropolitan area in the zone.