Antarctica/Casey

Time zone identifier: Antarctica/Casey

Current civil offset: +08:00 (+08)

Current DST state: Observing Standard Time

First standard time adoption: Adopted on 1969-01-01

Total recorded transitions: 17 transitions across 3 distinct offsets

Associated countries: AQ

Historical Offset Step Chart (1880 to Present)

Text summary: Antarctica/Casey shifted between 3 distinct offsets from 1969-01-01 through the modern era.

Complete Transition History (17 Transitions)

UTC Instant	Local Wall Time	Shift	Abbreviation	DST	Effect
`1969-01-01T00:00:00Z`	`1969-01-01 08:00:00`	+00:00 → +08:00	`+08`	No	gap
`2009-10-17T18:00:00Z`	`2009-10-18 05:00:00`	+08:00 → +11:00	`+11`	No	gap
`2010-03-04T15:00:00Z`	`2010-03-04 23:00:00`	+11:00 → +08:00	`+08`	No	overlap
`2011-10-27T18:00:00Z`	`2011-10-28 05:00:00`	+08:00 → +11:00	`+11`	No	gap
`2012-02-21T17:00:00Z`	`2012-02-22 01:00:00`	+11:00 → +08:00	`+08`	No	overlap
`2016-10-21T16:00:00Z`	`2016-10-22 03:00:00`	+08:00 → +11:00	`+11`	No	gap
`2018-03-10T17:00:00Z`	`2018-03-11 01:00:00`	+11:00 → +08:00	`+08`	No	overlap
`2018-10-06T20:00:00Z`	`2018-10-07 07:00:00`	+08:00 → +11:00	`+11`	No	gap
`2019-03-16T16:00:00Z`	`2019-03-17 00:00:00`	+11:00 → +08:00	`+08`	No	overlap
`2019-10-03T19:00:00Z`	`2019-10-04 06:00:00`	+08:00 → +11:00	`+11`	No	gap
`2020-03-07T16:00:00Z`	`2020-03-08 00:00:00`	+11:00 → +08:00	`+08`	No	overlap
`2020-10-03T16:01:00Z`	`2020-10-04 03:01:00`	+08:00 → +11:00	`+11`	No	gap
`2021-03-13T13:00:00Z`	`2021-03-13 21:00:00`	+11:00 → +08:00	`+08`	No	overlap
`2021-10-02T16:01:00Z`	`2021-10-03 03:01:00`	+08:00 → +11:00	`+11`	No	gap
`2022-03-12T13:00:00Z`	`2022-03-12 21:00:00`	+11:00 → +08:00	`+08`	No	overlap
`2022-10-01T16:01:00Z`	`2022-10-02 03:01:00`	+08:00 → +11:00	`+11`	No	gap
`2023-03-08T16:00:00Z`	`2023-03-09 00:00:00`	+11:00 → +08:00	`+08`	No	overlap

Notes from the Maintainers

Source: antarctica (Lines 1 to 85)

tzdb data for Antarctica and environs

This file is in the public domain, so clarified as of
2009-05-17 by Arthur David Olson.

From Paul Eggert (2025-08-16):
To keep things manageable, list only locations occupied year-round; see
Antarctic Facilities Information
https://www.comnap.aq/antarctic-facilities-information
for information.
Unless otherwise specified, we have no time zone information.

FORMAT is '-00' and STDOFF is 0 for locations while uninhabited.

Argentina - year-round bases
Belgrano II, Confin Coast, -770227-0343737, since 1972-02-05
Carlini, Potter Cove, King George Island, -6414-0602320, since 1982-01
Esperanza, Hope Bay, -6323-05659, since 1952-12-17
Marambio, -6414-05637, since 1969-10-29
Orcadas, Laurie I, -6016-04444, since 1904-02-22
San Martín, Barry I, -6808-06706, since 1951-03-21
(except 1960-03 / 1976-03-21)

Australia - territories
Heard Island, McDonald Islands (uninhabited)
previously sealers and scientific personnel wintered
Margaret Turner reports
https://web.archive.org/web/20021204222245/http://www.dstc.qut.edu.au/DST/marg/daylight.html
(1999-09-30) that they're UT +05, with no DST;
presumably this is when they have visitors.

year-round bases
Casey, Bailey Peninsula, -6617+11032, since 1969
Davis, Vestfold Hills, -6835+07759, since 1957-01-13
(except 1964-11 - 1969-02)
Mawson, Holme Bay, -6736+06253, since 1954-02-13

From Steffen Thorsen (2009-03-11):
Three Australian stations in Antarctica have changed their time zone:
Casey moved from UTC+8 to UTC+11
Davis moved from UTC+7 to UTC+5
Mawson moved from UTC+6 to UTC+5
The changes occurred on 2009-10-18 at 02:00 (local times).

Government source: (Australian Antarctic Division)
http://www.aad.gov.au/default.asp?casid=37079

We have more background information here:
https://www.timeanddate.com/news/time/antarctica-new-times.html

From Steffen Thorsen (2010-03-10):
We got these changes from the Australian Antarctic Division: ...

- Casey station reverted to its normal time of UTC+8 on 5 March 2010.
The change to UTC+11 is being considered as a regular summer thing but
has not been decided yet.

- Davis station will revert to its normal time of UTC+7 at 10 March 2010
20:00 UTC.

- Mawson station stays on UTC+5.

Background:
https://www.timeanddate.com/news/time/antartica-time-changes-2010.html

From Steffen Thorsen (2016-10-28):
Australian Antarctica Division informed us that Casey changed time
zone to UTC+11 in "the morning of 22nd October 2016".

From Steffen Thorsen (2020-10-02, as corrected):
Based on information we have received from the Australian Antarctic
Division, Casey station and Macquarie Island station will move to Tasmanian
daylight savings time on Sunday 4 October. This will take effect from 0001
hrs on Sunday 4 October 2020 and will mean Casey and Macquarie Island will
be on the same time zone as Hobart.  Some past dates too for this 3 hour
time change back and forth between UTC+8 and UTC+11 for Casey:
- 2018 Oct  7 4:00 - 2019 Mar 17 3:00 - 2019 Oct  4 3:00 - 2020 Mar  8 3:00
and now - 2020 Oct  4 0:01

From Paul Eggert (2023-12-20):
Transitions from 2021 on are taken from:
https://www.timeanddate.com/time/zone/antarctica/casey
retrieved at various dates.

Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]

Attributed Statements:

Paul Eggert (2025-08-16):

To keep things manageable, list only locations occupied year-round; see Antarctic Facilities Information https://www.comnap.aq/antarctic-facilities-information for information. Unless otherwise specified, we have no time zone information. FORMAT is '-00' and STDOFF is 0 for locations while uninhabited. Argentina - year-round bases Belgrano II, Confin Coast, -770227-0343737, since 1972-02-05 Carlini, Potter Cove, King George Island, -6414-0602320, since 1982-01 Esperanza, Hope Bay, -6323-05659, since 1952-12-17 Marambio, -6414-05637, since 1969-10-29 Orcadas, Laurie I, -6016-04444, since 1904-02-22 San Martín, Barry I, -6808-06706, since 1951-03-21 (except 1960-03 / 1976-03-21) Australia - territories Heard Island, McDonald Islands (uninhabited) previously sealers and scientific personnel wintered Margaret Turner reports https://web.archive.org/web/20021204222245/http://www.dstc.qut.edu.au/DST/marg/daylight.html (1999-09-30) that they're UT +05, with no DST; presumably this is when they have visitors. year-round bases Casey, Bailey Peninsula, -6617+11032, since 1969 Davis, Vestfold Hills, -6835+07759, since 1957-01-13 (except 1964-11 - 1969-02) Mawson, Holme Bay, -6736+06253, since 1954-02-13

Steffen Thorsen (2009-03-11):

Three Australian stations in Antarctica have changed their time zone: Casey moved from UTC+8 to UTC+11 Davis moved from UTC+7 to UTC+5 Mawson moved from UTC+6 to UTC+5 The changes occurred on 2009-10-18 at 02:00 (local times). Government source: (Australian Antarctic Division) http://www.aad.gov.au/default.asp?casid=37079 We have more background information here: https://www.timeanddate.com/news/time/antarctica-new-times.html

Steffen Thorsen (2010-03-10):

We got these changes from the Australian Antarctic Division: ... - Casey station reverted to its normal time of UTC+8 on 5 March 2010. The change to UTC+11 is being considered as a regular summer thing but has not been decided yet. - Davis station will revert to its normal time of UTC+7 at 10 March 2010 20:00 UTC. - Mawson station stays on UTC+5. Background: https://www.timeanddate.com/news/time/antartica-time-changes-2010.html

Steffen Thorsen (2016-10-28):

Australian Antarctica Division informed us that Casey changed time zone to UTC+11 in "the morning of 22nd October 2016".

Steffen Thorsen (2020-10-02, as corrected):

Based on information we have received from the Australian Antarctic Division, Casey station and Macquarie Island station will move to Tasmanian daylight savings time on Sunday 4 October. This will take effect from 0001 hrs on Sunday 4 October 2020 and will mean Casey and Macquarie Island will be on the same time zone as Hobart. Some past dates too for this 3 hour time change back and forth between UTC+8 and UTC+11 for Casey: - 2018 Oct 7 4:00 - 2019 Mar 17 3:00 - 2019 Oct 4 3:00 - 2020 Mar 8 3:00 and now - 2020 Oct 4 0:01

Paul Eggert (2023-12-20):

Transitions from 2021 on are taken from: https://www.timeanddate.com/time/zone/antarctica/casey retrieved at various dates. 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.