Pacific/Honolulu

Time zone identifier: Pacific/Honolulu

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

Associated countries: US

Aliases (Link targets): HST, Pacific/Johnston, US/Hawaii

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Historical Offset Step Chart (1880 to Present)

-12:00 -11:00 -10:00 -9:00 -8:00 1880 1900 1920 1940 1960 1980 2000 2020

Text summary: Pacific/Honolulu 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: northamerica (Lines 729 to 791)
The following switches don't make our 1970 cutoff.

Kiska observed Tokyo date and time during Japanese occupation from
1942-06-06 to 1943-07-29, and similarly for Attu from 1942-06-07 to
1943-05-29 (all dates American).  Both islands are now uninhabited.

Shanks writes that part of southwest Alaska (e.g. Aniak)
switched from -11:00 to -10:00 on 1968-09-22 at 02:00,
and another part (e.g. Akiak) made the same switch five weeks later.

From David Flater (2004-11-09):
In e-mail, 2004-11-02, Ray Hudson, historian/liaison to the Unalaska
Historic Preservation Commission, provided this information, which
suggests that Unalaska deviated from statutory time from early 1967
possibly until 1983:

Minutes of the Unalaska City Council Meeting, January 10, 1967:
"Except for St. Paul and Akutan, Unalaska is the only important
location not on Alaska Standard Time.  The following resolution was
made by William Robinson and seconded by Henry Swanson: Be it
resolved that the City of Unalaska hereby goes to Alaska Standard
Time as of midnight Friday, January 13, 1967 (1 A.M. Saturday,
January 14, Alaska Standard Time.)  This resolution was passed with
three votes for and one against."

Hawaii

From Arthur David Olson (2010-12-09):
"Hawaiian Time" by Robert C. Schmitt and Doak C. Cox appears on pages 207-225
of volume 26 of The Hawaiian Journal of History (1992). As of 2010-12-09,
the article is available at
https://evols.library.manoa.hawaii.edu/bitstream/10524/239/2/JL26215.pdf
and indicates that standard time was adopted effective noon, January
13, 1896 (page 218), that in "1933, the Legislature decreed daylight
saving for the period between the last Sunday of each April and the
last Sunday of each September, but less than a month later repealed the
act," (page 220), that year-round daylight saving time was in effect
from 1942-02-09 to 1945-09-30 (page 221, with no time of day given for
when clocks changed) and that clocks were changed by 30 minutes
effective the second Sunday of June, 1947 (page 219, with no time of
day given for when clocks changed). A footnote for the 1933 changes
cites Session Laws of Hawaii 1933, "Act. 90 (approved 26 Apr. 1933)
and Act 163 (approved 21 May 1933)."

From Arthur David Olson (2011-01-19):
The following is from "Laws of the Territory of Hawaii Passed by the
Seventeenth Legislature: Regular Session 1933," available (as of
2011-01-19) at American University's Pence Law Library. Page 85: "Act
90...At 2 o'clock ante meridian of the last Sunday in April of each
year, the standard time of this Territory shall be advanced one
hour...This Act shall take effect upon its approval. Approved this 26th
day of April, A. D. 1933. LAWRENCE M JUDD, Governor of the Territory of
Hawaii." Page 172: "Act 163...Act 90 of the Session Laws of 1933 is
hereby repealed...This Act shall take effect upon its approval, upon
which date the standard time of this Territory shall be restored to
that existing immediately prior to the taking effect of said Act 90.
Approved this 21st day of May, A. D. 1933. LAWRENCE M. JUDD, Governor
of the Territory of Hawaii."

Note that 1933-05-21 was a Sunday.
We're left to guess the time of day when Act 163 was approved; guess noon.

Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]

Attributed Statements:

David Flater (2004-11-09):

In e-mail, 2004-11-02, Ray Hudson, historian/liaison to the Unalaska Historic Preservation Commission, provided this information, which suggests that Unalaska deviated from statutory time from early 1967 possibly until 1983: Minutes of the Unalaska City Council Meeting, January 10, 1967: "Except for St. Paul and Akutan, Unalaska is the only important location not on Alaska Standard Time. The following resolution was made by William Robinson and seconded by Henry Swanson: Be it resolved that the City of Unalaska hereby goes to Alaska Standard Time as of midnight Friday, January 13, 1967 (1 A.M. Saturday, January 14, Alaska Standard Time.) This resolution was passed with three votes for and one against." Hawaii

Arthur David Olson (2010-12-09):

"Hawaiian Time" by Robert C. Schmitt and Doak C. Cox appears on pages 207-225 of volume 26 of The Hawaiian Journal of History (1992). As of 2010-12-09, the article is available at https://evols.library.manoa.hawaii.edu/bitstream/10524/239/2/JL26215.pdf and indicates that standard time was adopted effective noon, January 13, 1896 (page 218), that in "1933, the Legislature decreed daylight saving for the period between the last Sunday of each April and the last Sunday of each September, but less than a month later repealed the act," (page 220), that year-round daylight saving time was in effect from 1942-02-09 to 1945-09-30 (page 221, with no time of day given for when clocks changed) and that clocks were changed by 30 minutes effective the second Sunday of June, 1947 (page 219, with no time of day given for when clocks changed). A footnote for the 1933 changes cites Session Laws of Hawaii 1933, "Act. 90 (approved 26 Apr. 1933) and Act 163 (approved 21 May 1933)."

Arthur David Olson (2011-01-19):

The following is from "Laws of the Territory of Hawaii Passed by the Seventeenth Legislature: Regular Session 1933," available (as of 2011-01-19) at American University's Pence Law Library. Page 85: "Act 90...At 2 o'clock ante meridian of the last Sunday in April of each year, the standard time of this Territory shall be advanced one hour...This Act shall take effect upon its approval. Approved this 26th day of April, A. D. 1933. LAWRENCE M JUDD, Governor of the Territory of Hawaii." Page 172: "Act 163...Act 90 of the Session Laws of 1933 is hereby repealed...This Act shall take effect upon its approval, upon which date the standard time of this Territory shall be restored to that existing immediately prior to the taking effect of said Act 90. Approved this 21st day of May, A. D. 1933. LAWRENCE M. JUDD, Governor of the Territory of Hawaii." Note that 1933-05-21 was a Sunday. We're left to guess the time of day when Act 163 was approved; guess noon. 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.