HST

Time zone identifier: HST

Current civil offset: -10:00 (HST)

Current DST state: Observing Standard Time

First standard time adoption: Adopted on 1896-01-13

Local Mean Time (LMT): -10:31:26 based on geographic meridian

Total recorded transitions: 7 transitions across 4 distinct offsets

Historical Offset Step Chart (1880 to Present)

Text summary: HST shifted between 4 distinct offsets from 1896-01-13 through the modern era.

Complete Transition History (7 Transitions)

UTC Instant	Local Wall Time	Shift	Abbreviation	DST	Effect
`1896-01-13T22:31:26Z`	`1896-01-13 12:01:26`	-10:31:26 → -10:30	`HST`	No	gap
`1933-04-30T12:30:00Z`	`1933-04-30 03:00:00`	-10:30 → -09:30	`HDT`	Yes	gap
`1933-05-21T21:30:00Z`	`1933-05-21 11:00:00`	-09:30 → -10:30	`HST`	No	overlap
`1942-02-09T12:30:00Z`	`1942-02-09 03:00:00`	-10:30 → -09:30	`HWT`	Yes	gap
`1945-08-14T23:00:00Z`	`1945-08-14 13:30:00`	-09:30 → -09:30	`HPT`	Yes	offset-only
`1945-09-30T11:30:00Z`	`1945-09-30 01:00:00`	-09:30 → -10:30	`HST`	No	overlap
`1947-06-08T12:30:00Z`	`1947-06-08 02:30:00`	-10:30 → -10:00	`HST`	No	gap

Notes from the Maintainers

Source: backzone (Lines 1829 to 1838)

From Paul Eggert (2024-05-22):
The following zones pretend that standard time extends backward
indefinitely into the past, and so are ahistorical.
In current TZDB these entries are links to geographical locations
that agree with the ahistorical zones since 1970.
These are in numeric rather than alphabetic order.

Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]

Attributed Statements:

Paul Eggert (2024-05-22):

The following zones pretend that standard time extends backward indefinitely into the past, and so are ahistorical. In current TZDB these entries are links to geographical locations that agree with the ahistorical zones since 1970. These are in numeric rather than alphabetic order. Zone NAME STDOFF RULES FORMAT [UNTIL]

Years on Record

Methodology Note: The 1970 Rule

tzdb guarantees accuracy for timestamps from 1970 onwards. Transitions prior to 1970 represent best-effort historical reconstructions.