- tz - lists.iana.org

Alberta to follow British Columbia?
by Roozbeh Pournader May 15, 2026

May 15, 2026

I just ran into this: https://calgaryherald.com/opinion/columnists/bell-alberta-daylight-time-yea…

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BC considering “PacT” to abbreviate Pacific Time
by Paul Eggert May 14, 2026

May 14, 2026

The BC government is considering recommending the abbreviation “PacT” for Pacific Time as observed in British Columbia since 2026-03-09. Two draft TZDB patches are attached that would implement this. The first simply changes “MST” to “PacT” for timestamps starting 2026-11-01, in line with 2026b’s temporary hack to delay this transition because the downstream user CLDR v48.2 (2026-03-17) cannot support BC’s current timekeeping. The second patch removes the temporary hack, adjusting TZDB to better reflect BC’s timekeeping, in the hope that the temporary hack is no longer needed once the abbreviation changes from “MST” to “PacT”. I have not installed these patches into the TZDB development repository, as “PacT” is still under consideration. Comments are welcome as usual.

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Re: research on TZ list
by Michelle Bastian May 13, 2026

May 13, 2026

Dear all, I'm following up from a 2021 post where I let the list know about an academic research project I was planning which involved an analysis of the list discussion. I have now had a chance to finally start on this. I said at the time that I would get back in touch to ask permissions from anyone I would like to quote directly in my write up. Since the tz discussion list is searchable, this would mean that I could not fully anonymise those I quote as is the usual default practice in my field. This email to the full list is just to update everyone on the project, and let people know that I will contact some posters individually through the email they shared with this list. There is no pressure at all to agree, in fact you can ask me to remove any of your comments entirely. If I don't hear back after my first email I will send one follow up, but after that I will assume that you would rather not be involved. If you are happy to be included, I will share an information sheet that explains in detail what I'm asking for, and what to consider when making a decision, as well as consent form. Thanks all! Earlier post: https://lists.iana.org/hyperkitty/list/tz@iana.org/message/OTOYYCADZ7P5BUQX… With best wishes, Michelle. --- Dr Michelle Bastian Senior Lecturer in Environmental Humanities ESALA, Edinburgh College of Art, University of Edinburgh Level 1, Room 303B, The Maltings | Minto House, 20-22 Chambers Street, Edinburgh, EH1 1JZ | 0131 651 5779 https://www.eca.ed.ac.uk/profile/dr-michelle-bastian The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336. Is e buidheann carthannais a th' ann an Oilthigh Dh?n ?ideann, cl?raichte an Alba, ?ireamh cl?raidh SC005336.

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[PROPOSED] Adjust to GCC 16’s warnings
by Paul Eggert May 9, 2026

May 9, 2026

* Makefile (GCC_DEBUG_FLAGS): Add -Wfree-labels, -Wkeyword-macro. --- Makefile | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/Makefile b/Makefile index c0dde5be..3428e8fd 100644 --- a/Makefile +++ b/Makefile @@ -377,7 +377,8 @@ GCC_DEBUG_FLAGS = -DGCC_LINT -g3 -O3 \ -Wdeclaration-after-statement -Wdouble-promotion \ -Wduplicated-branches -Wduplicated-cond -Wflex-array-member-not-at-end \ -Wformat=2 -Wformat-overflow=2 -Wformat-signedness -Wformat-truncation \ - -Wimplicit-fallthrough=5 -Winit-self -Wlogical-op \ + -Wfree-labels -Wimplicit-fallthrough=5 -Winit-self \ + -Wkeyword-macro -Wlogical-op \ -Wmissing-declarations -Wmissing-prototypes \ -Wmissing-variable-declarations -Wnested-externs \ -Wnull-dereference \ -- 2.54.0

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[PROPOSED] Update commentary for Winnipeg in 1916 and 1960s
by Paul Eggert May 8, 2026

May 8, 2026

* northamerica: Update commentary in the light of Christian Cassidy’s article published two days ago. Although it seems that our data for America/Winnipeg in the 1960s are incorrect, as yet we have no better sources than Shanks & Pottenger. --- northamerica | 21 ++++++++++++++++----- 1 file changed, 16 insertions(+), 5 deletions(-) diff --git a/northamerica b/northamerica index 3e8641e1..6198e72e 100644 --- a/northamerica +++ b/northamerica @@ -1742,6 +1742,22 @@ Zone America/Toronto -5:17:32 - LMT 1895 # Manitoba +# From Paul Eggert (2026-05-08): +# For 1916 timestamps America/Winnipeg covers only a small region. See: +# Cassidy C. Winnipeg's 100-year history with daylight time. +# Winnipeg Free Press. 2026-05-06. +# https://www.winnipegfreepress.com/our-communities/correspondents/2026/05/06… +# Of the 1916 experiment, Cassidy writes: "As rural areas and nearby +# urban centres such as Selkirk and Brandon did not adopt DST, the +# City of Winnipeg essentially had its own time zone." Cassidy also +# writes that province-wide DST came into effect on 1963-05-12. +# +# Shanks & Pottenger write that Winnipeg did not observe DST in 1964 and 1965. +# Although dubious in the light of Cassidy's article, we lack a better source. +# Perhaps S&P's data are for the train stations, not for the city? +# Also, S&P say Manitoba switched at 02:00 (not 02:00s) starting in 1966. +# Since 02:00s is clearly correct for 1967 on, assume 02:00s in 1966 too. + # From Rob Douglas (2006-04-06): # the old Manitoba Time Act - as amended by Bill 2, assented to # March 27, 1987 ... said ... @@ -1756,11 +1772,6 @@ Zone America/Toronto -5:17:32 - LMT 1895 # the 1987 version would apply - the changeover was at 2:00 Central # Standard Time (i.e. not until 3:00 Central Daylight Time). -# From Paul Eggert (2006-04-10): -# Shanks & Pottenger say Manitoba switched at 02:00 (not 02:00s) -# starting 1966. Since 02:00s is clearly correct for 1967 on, assume -# it was also 02:00s in 1966. - # Rule NAME FROM TO - IN ON AT SAVE LETTER/S Rule Winn 1916 only - Apr 23 0:00 1:00 D Rule Winn 1916 only - Sep 17 0:00 0 S -- 2.51.0

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Greenland to abolish DST starting in 2028
by Paul Eggert May 7, 2026

May 7, 2026

The Copenhagen Post reported today[1] that the Naalakkersuisut Government of Greenland supports abolishing daylight saving time, effective January 1, 2028, so that most of Greenland will remain on UTC-2 indefinitely after that. The premier Jens-Frederik Nelson confirmed the intention to issue a new decree to that effect. Although I don't know the details, my impression is that this will affect America/Nuuk and America/Scoresbysund but not America/Thule (which uses US rules, not EU) and America/Danmarkshavn (which does not observe DST). The practical date for this change is 2028-03-26, which is when Greenland would otherwise spring forward, so we have plenty of time to wait for the details in the official decree and install a change to TZDB well before the practical date. [1]: Greenland to abolish daylight saving time from 2028. Copenhagen Post. 2026-05-06. <https://cphpost.dk/2026-05-06/news/round-up/greenland-to-abolish-daylight-s…>

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Elsewhere in Canada
by Tim Parenti May 6, 2026

May 6, 2026

Manitoba Premier Wab Kinew says he thinks "the days of Manitoba switching the clocks twice a year are pretty much at the end," though there appears to be some internal wrangling over which way the clocks should move for the final time. "If we move to permanent standard time, you could have a Prairie time zone" shared between Manitoba, Saskatchewan, and Alberta. https://www.cbc.ca/news/canada/manitoba/time-change-kinew-9.7176389 Manitoba's Legislative Assembly is in session through 1 June before its summer recess, though a decision to adopt such a "Prairie time zone" on year-round UTC−6 likely wouldn't affect wall-clock times until 14 March 2027. So any legislation, if forthcoming, may not happen until the fall. Meanwhile, in Atlantic Canada, "Nova Scotia Premier Tim Houston said he is open to the idea but only if neighbouring provinces did too," while New Brunswick Premier Susan Holt says "we would want to do it in concert with our Atlantic peers. But this is premature." https://www.msn.com/en-ca/news/canada/as-alberta-moves-to-end-time-changes-… https://www.pressreader.com/canada/telegraph-journal/20260429/2815565924285… -- Tim Parenti

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America/Cranbrook
by Chris Walton May 6, 2026

May 6, 2026

Heads up: The *Regional District of East Kootenay* is planning to move to year-round Mountain Standard Time (MST) on November 1, 2026. The district will seek approval from the province (British Columbia). I am skepitcal that they really need provincial approval, but I guess there is no harm in seeking it. In practical terms the district would move from MDT to MST on November 1 as per usual. After that, the clocks would stay fixed on MST. Currently most of East Kootenay uses the *America/Edmonton* TZ ID. There is a very small area in the southwest corner that uses *America/Creston*. If the change is approved, we would need a new TZ ID... probably something like "*America/Cranbrook"*. https://www.rdek.bc.ca/news/entry/rdek_board_moves_to_transition_to_year_ro… Columbia-Shuswap Regional District lies to the north of East Kootenay Regional District. Some areas of Columbia-Shuswap are already on year-round MST and some areas (including the town of Golden) use MST/MDT. I would not be surprised if all of Columbia-Shuswap eventually adopts year-round MST. If that happens, the entire province of BC would be aligned on year-round MST. -chris

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[PROPOSED] Check for NEWS typos similar to 2026b’s
by Paul Eggert April 23, 2026

April 23, 2026

* Makefile (check_mild): Depend on new check. (news.ck): New check. * NEWS: Reword to pass check. --- Makefile | 8 +++++++- NEWS | 2 +- 2 files changed, 8 insertions(+), 2 deletions(-) diff --git a/Makefile b/Makefile index 1e0a5903..c0dde5be 100644 --- a/Makefile +++ b/Makefile @@ -913,7 +913,7 @@ tzselect: tzselect.ksh version check: check_mild back.ck now.ck check_mild: check_web check_zishrink \ character-set.ck white-space.ck links.ck mainguard.ck \ - name-lengths.ck slashed-abbrs.ck sorted.ck \ + name-lengths.ck news.ck slashed-abbrs.ck sorted.ck \ tables.ck ziguard.ck tzs.ck # True if UTF8_LOCALE does not work; @@ -1083,6 +1083,12 @@ zishrink-posix.ck zishrink-right.ck: \ rm -fr $@d t-$@d shrunk-$@d touch $@ +# Check that NEWS has data release versions and dates in reverse order. +news.ck: NEWS + grep '^Release [0-9][0-9][0-9][0-9]' NEWS | LC_ALL=C sort -cru + sed -n '/ -0000$$/!s/^Release [^ ]*//p' NEWS|LC_ALL=C sort -cru + touch $@ + clean_misc: rm -fr *.ckd *.dir rm -f *.ck *.core *.o *.out *.t core core.* \ diff --git a/NEWS b/NEWS index ea52e67e..fb1ced71 100644 --- a/NEWS +++ b/NEWS @@ -6666,7 +6666,7 @@ few (e.g., code2012c-data2012d) have tarballs with mixed version numbers. Recent releases also come in an experimental format consisting of a single tarball tzdb-R.tar.lz with extra data. -Release timestamps are taken from the release's commit (for newer, +A release's timestamp is taken from the release's commit (for newer, Git-based releases), from the newest file in the tarball (for older releases, where this info is available) or from the email announcing the release (if all else fails; these are marked with a time zone -- 2.51.0

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[tz-announce] 2026b release of tz code and data available
by Paul Eggert via tz-announce April 23, 2026

April 23, 2026

The 2026b release of the tz code and data is available. As Tim mentioned yesterday[1], this release’s main impetus is British Columbia’s decision to stop changing its clocks and stay on permanent UTC-07, which affects BC’s UTC offsets starting 2026-11-01 at 02:00. Since this change will likely cause problems downstream as CLDR’s latest release cannot handle it, we’re pushing out this release now so that downstream has some time to test and reprogram. Quite possibly we’ll need another release soon to accommodate proposed changes in Alberta and Northwest Territories. [1]: https://lists.iana.org/hyperkitty/list/tz@iana.org/thread/LZIJFAY2K4OXXCAGF… There is an embarrassing typo in the 2026b release: its NEWS file's third line has the wrong release number. I applied the following patch to the development version on GitHub and this patch should appear in the 2026c release. diff --git a/NEWS b/NEWS index a0042701..ea52e67e 100644 --- a/NEWS +++ b/NEWS @@ -3 +3 @@ News for the tz database -Release 2026a - 2026-04-22 23:06:43 -0700 +Release 2026b - 2026-04-22 23:06:43 -0700 The 2026b release contains the following changes: Briefly: British Columbia moved to permanent -07 on 2026-03-09. Some more overflow bugs have been fixed in zic. Changes to future timestamps British Columbia’s 2026-03-08 spring forward was its last foreseeable clock change, as it moved to permanent -07 thereafter. (Thanks to Arthur David Olson.) Although the change to permanent -07 legally took place on 2026-03-09, temporarily model the change to occur on 2026-11-01 at 02:00 instead. This works around a limitation in CLDR v48.2 (2026-03-17). This temporary hack is planned to be removed after CLDR is fixed. Changes to code zic no longer mishandles a last transition to a new time type. zic no longer overflows a buffer when generating a TZ string like "PST-167:59:58PDT-167:59:59,M11.5.6/-167:59:59,M12.5.6/-167:59:59", which can occur with adversarial input. (Thanks to Naveed Khan.) zic no longer generates a longer TZif file than necessary when an earlier time zone abbreviation is a suffix of a later one. As a nice side effect, zic no longer overflows a buffer when given a long series of abbreviations, each a suffix of the next. (Buffer overflow reported by Arthur Chan.) zic no longer overflows an int when processing input like ‘Zone Ouch 2147483648:00:00 - LMT’. The int overflow can lead to buffer overflow in adversarial cases. (Thanks to Naveed Khan.) zic now checks for signals more often. Here are links to the release files: https://www.iana.org/time-zones/repository/releases/tzcode2026b.tar.gz https://www.iana.org/time-zones/repository/releases/tzdata2026b.tar.gz https://www.iana.org/time-zones/repository/releases/tzdb-2026b.tar.lz The following convenience links are also available, although they may point to the previous release until the relevant caches are refreshed: https://www.iana.org/time-zones/repository/tzcode-latest.tar.gz https://www.iana.org/time-zones/repository/tzdata-latest.tar.gz https://www.iana.org/time-zones/repository/tzdb-latest.tar.lz Links are also available via plain HTTP, and via FTP from ftp://ftp.iana.org/tz/releases with the same basenames as above. Each release file has a GPG signature, which can be retrieved by appending ".asc" to the above URLs. Copies of these signatures are appended to this message. This release corresponds to commit 48c25a1ba86cb602990c0573aba7795417931bb4 dated 2026-04-22 23:06:43 -0700 and tagged '2026b' in the development GitHub repository at <https://github.com/eggert/tz>. Here are the SHA-512 checksums for the release files: 55b44d52a83c9db151be32c3d78376ea7f9d4311ef15ed6fe34b855b08fc546531e51309d178d9c175a6d5d7d0b058440e45a55d200ca8925e3798dac9bc739f tzcode2026b.tar.gz a44882258c0a7fbe587e8b73d6bb3cd5be7d4788976ea742adbbf176eb3b33e5bd7d1714b2fffe2972b1a42e7335eac39ed0bd63e819bb421550f8cae1df4f2f tzdata2026b.tar.gz 5ec7f74f14cd2c70a0730e3690e82bd0ba889ac26c96397c16aa08005473c2c86feb47958b52e0301810c8eb908e6d8faf998ffae75b2337a912cc9e52c0f9e9 tzdb-2026b.tar.lz Here are GPG digital signatures for the release files: -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEfjeSqdis99YzvBWI7ZfpDmKqfjQFAmnpt34ACgkQ7ZfpDmKq fjSZew//brt18HiMD/tgxJ1CdjvvzDIZ4P0xWsVuxG4MjkC4821zYCfhDYLZ9Zdb /8wCi63uecmK2JsGjxzz+raX4ppHhZpg31a70KlyU9MarISVB2ldPqYDn+Xc98lR XIKj1ahtzyJoNu/67ZbCT7Ih/Wp8hwdlEFivjq00lnt+M2XCeINq9Cy3guisx3/8 dCziZEqoJFXDsdWmCvKZ93U/o7Xq8x7d9nfRjeBlX8VZMXuSnY3WkhLBRl+2Zgml ECeohhLMBuR6dFNOW6qwlsZGXfDb/Nq1NPsxIKqJ5Lv1K8Sj0h4icsGDMRrLvlZM qfNpsjWZQcH9JErR5hfB/Y6INRsKomRamul9LdlEAauMwO287eR8r5LrADMiAvPR jBVqmceAmgS+34BpRmMUfLwQJmEELbK8xzcdW8e41jrQQ8SuyqXQeYBjgjm3v7gc sA1HyWwDRn6276DQATonELOzREctHLIp2jfRGLAwngAl2CzqkhLZgBEHvdZbqW/s RbZLOk0u/y3Trd+dyFcLq/gxNSZQYQqpDmRiYNkb0vl02lu3lbZ1o3dmdF/AZ70U evj6z5iXztdKCQb9ZkecjNXncPDQNPoO1bJqm1QNYvUToMDNnJdu12qva+skNUyt HE54zxjcKv78bhm2ufXcqt4Ju/onyACTkSDQeCEzIzdBu9abVgw= =7394 -----END PGP SIGNATURE----- -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEfjeSqdis99YzvBWI7ZfpDmKqfjQFAmnpt34ACgkQ7ZfpDmKq fjTFTxAAisuje9O4OTkSUUQ4nHuZOHQW/1FNGXmIb/bGnAGAwOrGqiLuyQ0kJYxk Gdp4cTXEu5+NyQXeBPFtjBNbZO2cMC80rvl9/h3qUlbYG+ydhY0bjDglV3BEP/U/ OrP4pQsNjHeSl+p+3VSq7fAtOGcCRkBQrbEy5yXN5HzYJyCH4GAE1HZNNYKbCzAm hIxspmu6zjeN4xeLsXrB7DfiP7BJydrxk1LShU4zwmwJdmkH8dCGnDW4Kipz+tWF 2W8P4braXTAWCswLhOC8xYZLJKxf1nWS3dyo3i1IfnRciGD0O9dyLsJmlHxS4/34 Ometm9XahPHPiWvjBoqubKEfp6B+AlmmP9D1jM0BY7seuz2oxFUE7YW5+4cO4VhJ soWTDCKjyzo+wgflw3brv7j5AFP7tA7To6fbQ0W0oAmSRFQ10MA3JB0GSgn45SST 49C9jQ7U0XcroeIuoWs/1MbAz+qgCLk9QdijxNWsvk5S5h88FKLckVkEUUNgUSL/ F3z4h2Af6KpWq/n3wL97gwdis8cwxWScL3ZpfikiMJbEGuaIHabiw7C+r/dQssW0 7SbG01yZWgn3HtJBfELs1cmqWCUN4F+Y28um0Y4VYHTpSnNuVHBJ1wtfqCSatWYC wQa+n7KtBEGpY7BbSDZ/oGuqfDzpgR41F1tX7ZRa5y24zWHRQLQ= =eO2u -----END PGP SIGNATURE----- -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEfjeSqdis99YzvBWI7ZfpDmKqfjQFAmnpt38ACgkQ7ZfpDmKq fjTopg//ViAbiWmRZnu7F5owFRPySQWCSM1RJfBWOTL/UJjSArP2JbkOudcgeXZo Wj6fk1soY8w3o6CJACq12HhUAjQq6/mCupTyDSgOETMn2x/ZknuE407MOMc0t51t iYnfICJNYs1u1uRC/b7PEALYT7lt3Ab6QGe5iO2kVrFqJoB1AxRDIQlfPAHiRILY Abbt9avcL+k76idhSC782BmAFqtogPeHBVYQzBOgw/LfWGQ8ckkk66f4X8E6QMzA CkDSt/bAWIM/iVKw6ag4VBvIbzY2sR1EieN2GlHj5Dx6xMBlQdDpETgTIfNYG7si Ndai7vbMh+Gff5JfYiKq94WJ2uAP4jI3phN2NXpcYwc0OmEEMlYc/lcIlje3Bb3o Y+yop6RoVQpN6zbzLnuCMiDmy1SB2yhWpYQm/bqR1Qsb8vBfWBD3fvdscWXabDl8 m3ii38melVIdjSR18Qf3j9MOXefHo3xu0t00/ppPCwnuKKbhSItvTI9vg8BxqWL8 7iZYhNBkoJTIpgmTaHAggNUKNoa3mNYTuwJr7o/i4Bhki2ggzR5dKiKE9PAXSLaG 1tvCoWVVA3gGklkxFYnUncghC/YbEBDYWlaXbfgOC/+fhix7HnRCNcwckxlww86m gZCa2DcTBWiVQ6PP/6LzgHgNn7mhriVs0cGGVOlTL/h/zjm5CDw= =1+mL -----END PGP SIGNATURE-----

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