Time zone · Americas
HDT
Hawaii-Aleutian Daylight Time
Hawaii-Aleutian Daylight Time (HDT) shifts life in this far-flung U.S. region forward by pulling evenings brighter at the cost of earlier dawns. These isolated communities leap into HDT every spring to stretch their usable daylight in a place where the ocean already locks them into one hemisphere’s rhythm.
Friday, June 5, 2026
Current offset
UTC-09:00
Daylight · HDT
Daylight saving
Active
Reverts 1 Nov 2026
IANA zones
1
1 observe DST, 0 don't
DST offset
—
No summer variant
About HDT
Standard time, with a summer shift.
Hawaii-Aleutian Daylight Time (HDT) shifts life in this far-flung U.S. region forward by pulling evenings brighter at the cost of earlier dawns. These isolated communities leap into HDT every spring to stretch their usable daylight in a place where the ocean already locks them into one hemisphere’s rhythm.
IANA zones · the technical identifiers
The zone that resolve to HDT.
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 HDT is used
One country.
Same offset · UTC-09:00
Other zones at UTC-09:00 right now.
These named zones share HDT's offset today. When daylight saving rules differ, they drift apart for part of the year.
Frequently asked questions
Common questions about HDT, daylight saving, and how to handle it in software. Can't find what you need? Email [email protected].
- When does Hawaii-Aleutian Daylight Time start and end?
- It typically begins on the second Sunday in March and ends in early November, so most of the warmer months fall under the HDT offset.
- Why does this region observe daylight saving time?
- The advance-push of the clock minimizes the impact of extreme latitude swings, helping residents and businesses plan around longer evening light across the islands.
- Is Adak the only major place keeping HDT?
- Yes — as the primary representative, its Aleutian coordinates make this far-western U.S. community the standout keeper for the code.
- How does HDT affect neighbors like Hawaii?
- Despite Hawaii cozying up under its own Hawaii Standard Time, Adak and the Aleutians set the tempo for HDT, making cross-region scheduling a careful dance by a full hour.
- What is the strangest quirk about living in HDT?
- These islanders balance their clocks with seasonal logistics: mail, flights, and school runs all tweak annually to match the special, solitary HDT tick.
- Can travelers expect smooth digital devices in HDT territory?
- Most modern phones and apps auto-adjust, but travelers still prepare for early dawns and watch carefully for dead zones where “smart” settings might skip a beat.
- How rare is the HDT label?
- Very rare — just one member zone (America/Adak) is prominent enough to carry the torch.
- Does HDT’s agenda align with other global daylight shifts?
- Not quite: this move is unique to the United States, specifically not shared with Canada or Europe.
- Why would a traveler plan around HDT transitions?
- Missing the annual shift could upend ferry departures or park hours, especially since the times rarely rebound from the prior year's schedule.
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