Technical Specifications & Standards
Official chronometric properties, ISO standards, and international database registry identifiers for Hawaii-Aleutian Standard Time:
Daylight Saving Time (DST) Transitions
⬆️ Spring Forward (Clocks Advance)
Hawaii does not observe DST; Aleutian Islands advance to HADT on the second Sunday in March
⬇️ Fall Back (Clocks Return)
Aleutian Islands return to HAST on the first Sunday in November
Observing Jurisdictions & Subdivisions
1 Sovereign NationsSovereign nations, administrative subdivisions, and regional territories officially operating under HAST:
Regional Subdivisions & Territory Details
Financial Markets & Trading Hours
Connects transpacific Asian and US mainland financial transactions, operating as the westernmost US commercial time zone.
Local Hours: 08:30 - 16:30 HAST
UTC Window: 18:30 - 02:30 UTC
Major Cities in HAST
Primary metropolitan centers and financial hubs observing this time zone:
Adoption History & Astronomical Facts
Year Established: 1947
Hawaii standardized on UTC-10 on June 8, 1947, moving from its previous UTC-10:30 offset. Hawaii opted out of the Uniform Time Act of 1966 in 1967, maintaining UTC-10 year-round, while Alaska's Aleutian Islands observe seasonal DST.
Hawaii is one of only two US states (along with most of Arizona) that do not observe Daylight Saving Time, keeping clocks on UTC-10 throughout the entire year.
Frequently Asked Questions about HAST
Does Hawaii observe Daylight Saving Time?
No. Hawaii stays on Hawaii-Aleutian Standard Time (UTC-10) all year round.
What is the time difference between Hawaii and Los Angeles?
Hawaii is 2 hours behind Los Angeles during Pacific Standard Time (winter) and 3 hours behind during Pacific Daylight Time (summer).
Do the Aleutian Islands observe daylight saving?
Yes. Alaska's Aleutian Islands observe daylight saving time, shifting to HADT (UTC-9) in summer.