Technical Specifications & Standards
Official chronometric properties, ISO standards, and international database registry identifiers for Hawaii Standard Time:
Daylight Saving Time (DST) Transitions
⬆️ Spring Forward (Clocks Advance)
None (Hawaii has never used daylight saving under the Uniform Time Act)
⬇️ Fall Back (Clocks Return)
None
Observing Jurisdictions & Subdivisions
2 Sovereign NationsSovereign nations, administrative subdivisions, and regional territories officially operating under HST:
Regional Subdivisions & Territory Details
Financial Markets & Trading Hours
Operates during the late afternoon and evening hours of the US mainland, and during the morning of the following calendar day in Tokyo and Sydney.
Local Hours: 08:00 - 17:00 HST
UTC Window: 19:00 - 03:00 UTC
Major Cities in HST
Primary metropolitan centers and financial hubs observing this time zone:
Adoption History & Astronomical Facts
Year Established: 1896
Adopted by the Republic of Hawaii in January 1896 as UTC-10:30. In 1947, the territorial legislature rounded the time to UTC-10:00 to simplify maritime and radio communications with the mainland.
Because Hawaii sits close to the equator at 21 degrees north latitude, the difference between the longest and shortest days of the year is only about two and a half hours, making daylight saving practical changes unnecessary.
Frequently Asked Questions about HST
What does HST stand for?
HST stands for Hawaii Standard Time, which is ten hours behind Coordinated Universal Time (UTC-10).
Does Hawaii use daylight saving time?
No. Hawaii stays on HST (UTC-10) all year round.
What is the time difference between Hawaii and California?
Hawaii is two hours behind California during the winter (PST), and three hours behind California during the summer (PDT).