Time Zone Changes in 2025

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

Attached to: Antarctica/Casey (antarctica)

Roozbeh Pournader (2025-03-18):

... the exact time of Iran's transition from +0400 to +0330 ... was Friday
1357/8/19 AP=1978-11-10. Here's a newspaper clip from the Ettela'at
newspaper, dated 1357/8/14 AP=1978-11-05, translated from Persian
(at https://w.wiki/DUEY):
Following the government's decision about returning the official time
to the previous status, the spokesperson for the Ministry of Energy
announced today: At the hour 24 of Friday 19th of Aban (=1978-11-10),
the country's time will be pulled back half an hour.

Attached to: Iran (asia)

Robert H. van Gent (2025-07-21):

The most recent issue of the Annuaire [par le Bureau des Longitudes]
on Gallica (2021) ... lists information for France
https://gallica.bnf.fr/ark:/12148/bpt6k9127672b/f52.item

Attached to: France (europe)

Paul Eggert (2025-07-21):

Go with the 2020 Annuaire (published 2021) except as noted below.

Attached to: France (europe)

Robert H. van Gent (2025-07-22):

There is a curious history behind the erroneous date for the start of
daylight saving in France in 1923 as listed in the current issues of
the Annuaire du Bureau des Longitudes.  [See:]
https://lists.iana.org/hyperkitty/list/tz@iana.org/message/MYQEJMSXO2AIEZ3UIXZKMTTAIPY7KNT2/

Attached to: France (europe)

Brian Inglis (2025-07-23):

Légifrance JORF No. 0073 du 15 mars 1922
https://www.legifrance.gouv.fr/jorf/jo/id/JORFCONT000000008324
Légifrance JORF No. 0139 du 25 mai 1923
https://www.legifrance.gouv.fr/jorf/jo/id/JORFCONT000000008416

Attached to: France (europe)

Paul Eggert (2025-07-23):

The latter specifies March's last Saturday at 23:00 to October's first
Saturday at 24:00, except that if neighboring allies agree the dates
can be moved to April's third Saturday and September's third Saturday.
Apparently spring 1923 was tricky.  DISHO writes that in 1930,
because of Easter, the transitions were Apr 12 and Oct 5.
Use the 2020 Annuaire dates, except for spring 1923 where
Shanks & Pottenger's May 26 matches the dates given in the 1924 and
1961-2001 issues of the Annuaire.

Attached to: France (europe)

Rob van Gent (2025-07-23):

Another useful source for historical time zone information appears to be
a series of circulars with the title "Standard Time Throughout the World"
issued between 1925 and 1950 by the U.S. Bureau of Standards.
I found the following issues online:
https://nvlpubs.nist.gov/nistpubs/Legacy/circ/nbscircular280.pdf (1925)
https://nvlpubs.nist.gov/nistpubs/Legacy/circ/nbscircular399.pdf (1932)
https://nvlpubs.nist.gov/nistpubs/Legacy/circ/nbscircular406.pdf (1935)
https://nvlpubs.nist.gov/nistpubs/Legacy/circ/nbscircular496.pdf (1950)

Attached to: Canada (northamerica)

Paul Eggert (2025-03-20):

Also see the 1912-06-17 front page of The Evening Sunbeam,
reproduced in: Richardson M. "Daylight saving was a confusing
time in Orillia" in the 2025-03-15 Orillia Matters. Richardson writes,
"The first Sunday after the switch was made, [DST proponent and
Orillia mayor William Sword] Frost walked into church an hour late.
This became a symbol of the downfall of daylight saving in Orillia."
The mayor became known as "Daylight Bill".
https://www.orilliamatters.com/local-news/column-daylight-saving-was-a-confusing-time-in-orillia-10377529

Attached to: Toronto (northamerica)

Alois Treindl (2025-07-29):

I did a quick newspaper archive research on https://hndm.iib.unam.mx/
and found that Periódico Oficial del Estado de Baja California Norte
(1973-04-20) states clearly that DST was observed from last Sunday
in April to last Sunday in October....  I have a few more data from the
official bulletin for DST begin or end in Baja California 1964 1967 1969
1972 1973 (already sent) 1974 1975 1976 I do not know whether it is safe to
assume that it also applied in the years where I did not yet find proof.
The 1974 end of DST contains a reference to an Acuerdo of 1973-dec-20 which
I could not find....  One might assume that Baja California, which followed
US-CA in all these other yours, did the same.

Attached to: Mexico (northamerica)

Paul Eggert (2025-08-04):

Assume that Tijuana agreed with San Diego from 1953 through 1996,
as this agrees with Alois Treindl's data and with Shanks.
For now, keep the slightly-different 1948/1952 history for Baja California,
as we have no information on whether 1948/1952 clocks in Tijuana followed
the decrees or followed San Diego.

Attached to: Mexico (northamerica)

Paul Eggert (2025-08-04):

Unfortunately we have no data to track this informal practice.

Attached to: Mexico (northamerica)

Tim Parenti (2025-03-22):

Decreto 307 of 2014 of the Ministry of the Interior and Public Security,
promulgated 2014-01-30 and published 2014-02-19:
https://www.diariooficial.interior.gob.cl/media/2014/02/19/do-20140219.pdf#page=1
https://www.bcn.cl/leychile/navegar?idNorma=1059557

Attached to: Chile (southamerica)

Tim Parenti (2025-03-22):

Decreto 106 of 2015 of the Ministry of the Interior and Public Security,
promulgated 2015-01-27 and published 2015-03-03:
https://www.diariooficial.interior.gob.cl/media/2015/03/03/do-20150303.pdf#page=1
https://www.bcn.cl/leychile/navegar?idNorma=1075157

Attached to: Chile (southamerica)

Tim Parenti (2025-03-22):

Decreto 253 of 2016 of the Ministry of the Interior and Public Security,
promulgated 2016-03-16 and published 2016-03-18.
https://www.diariooficial.interior.gob.cl/media/2016/03/18/do-20160318.pdf#page=1
https://www.bcn.cl/leychile/navegar?idNorma=1088502

Attached to: Chile (southamerica)

Tim Parenti (2025-03-22):

Decreto 1820 of 2016 of the Ministry of the Interior and Public Security,
promulgated 2016-12-02 and published 2017-01-17:
https://www.diariooficial.interior.gob.cl/publicaciones/2017/01/17/41660/01/1169626.pdf
https://www.bcn.cl/leychile/Navegar?idNorma=1099217
Model this as a change to standard offset effective 2016-12-04.

Attached to: Chile (southamerica)

Tim Parenti (2025-03-22):

Decreto 1286 of 2018 of the Ministry of the Interior and Public Security,
promulgated 2018-09-21 and published 2018-11-23:
https://www.diariooficial.interior.gob.cl/publicaciones/2018/11/23/42212/01/1498738.pdf
https://www.bcn.cl/leychile/Navegar?idNorma=1125760

Attached to: Chile (southamerica)

Tim Parenti (2025-03-22):

Decreto 143 of 2022 of the Ministry of the Interior and Public Security,
promulgated 2022-03-29 and published 2022-03-31:
https://www.diariooficial.interior.gob.cl/publicaciones/2022/03/31/43217-B/01/2108910.pdf
https://www.bcn.cl/leychile/Navegar?idNorma=1174342

Attached to: Chile (southamerica)

Tim Parenti (2025-03-22):

Decreto 224 of 2022 of the Ministry of the Interior and Public Security,
promulgated 2022-07-14 and published 2022-08-13:
https://www.diariooficial.interior.gob.cl/publicaciones/2022/08/13/43327/01/2172567.pdf
https://www.bcn.cl/leychile/navegar?idNorma=1179983

Attached to: Chile (southamerica)

Yonathan Dossow (2025-03-20):

[Aysén] region will keep UTC-3 all year...
https://www.cnnchile.com/pais/region-de-aysen-mantendra-horario-de-verano-todo-el-ano_20250320/
https://www.latercera.com/nacional/noticia/tras-consulta-ciudadana-region-de-aysen-mantendra-el-horario-de-verano-durante-todo-el-ano/
https://x.com/min_interior/status/1902692504270672098

Attached to: Chile (southamerica)

Tim Parenti (2025-03-22):

Decreto 93 of 2025 of the Ministry of the Interior and Public Security,
promulgated 2025-03-11 and published 2025-03-20:
https://www.diariooficial.interior.gob.cl/publicaciones/2025/03/20/44104/01/2624263.pdf
https://www.bcn.cl/leychile/Navegar?idNorma=1211955
Model this as a change to standard offset effective 2025-03-20.

Attached to: Chile (southamerica)