The 2026c release of the tz code and data is available. This release’s
main urgency is Alberta’s decision to stop changing its clocks and stay
on permanent UTC-06, which has a practical effect starting 2026-11-01 at
02:00. Like the similar British Columbia changes in the previous
release, there will likely be problems downstream as CLDR’s latest
release cannot handle it as specified. So we’re releasing now so that
downstream has some time to test and adjust.
Also, Morocco is moving to permanent UTC on 2026-09-20. This will likely
cause fewer problems among downstream CLDR users.
Although quite possibly we’ll soon need another TZDB release to
accommodate similar changes planned for Northwest Territories, these
changes have not been formalized yet.
This release contains the following changes:
Briefly:
Alberta moved to permanent -06 on 2026-06-18.
Morocco moves to permanent +00 on 2026-09-20.
More integer overflow bugs have been fixed in zic.
Changes to future timestamps
Alberta’s 2026-03-08 spring forward was its last foreseeable clock
change, as it moved to permanent -06 thereafter. (Thanks to Roozbeh
Pournader and others.) Model this with its traditional abbreviation
CST. Although the change to permanent -06 legally took place on
2026-06-18, temporarily model the change to occur on 2026-11-01 at
02:00 instead, for the same reason we introduced a similarly
temporary hack for British Columbia in 2026b.
Although another TZDB release will likely be needed soon because
Northwest Territories will likely follow Alberta, the legal
formalities have not yet taken place.
Morocco plans to move back to permanent UTC, without daylight
saving time transitions, on 2026-09-20 at 02:00. This also
affects Western Sahara.
Changes to code
zic no longer overflows integers when processing outlandish input
like ‘Zone Ouch 0 - LMT 9223372036854775807’, ‘Zone Ouch 0
2562047788015215 LMT’, ‘Zone Ouch -2562047788015215:30:08 - LMT’,
and ‘Zone Ouch -2562047788015215:30:08 - %%z’. This avoids
undefined behavior in C. (Problems reported by Naveed Khan.)
On platforms that have EFTYPE, tzalloc now fails with errno set to
EFTYPE, not EINVAL, if it detects that the TZif file has an
invalid format or is not a regular file. Formerly it did this
only on NetBSD, and only when the file was not a regular file.
Unprivileged programs no longer require TZif files to be regular
files or reject relative names containing ".." components. This
reverts to the more-permissive 2025b behavior, as the stricter
behavior did not catch on in FreeBSD.
zic now reports any failure to remove a temporary file when
cleaning up after a previous failure. (Problem reported by Tom
Lane.)
Changes to commentary
Northwest Territories is expected to move to permanent -06 prior to
2026-11-01 02:00, when clocks would otherwise fall back. (Thanks to
Tim Parenti and James Bellaire.) Model this with its traditional
abbreviation CST. Unfortunately the change is not yet official, so
it is currently present only as comments that can be uncommented as
needed.
Changes to build procedure
The undocumented ‘typecheck’ Makefile check rule has been removed.
It stopped working in 2025a and evidently nobody noticed.
The rule was superseded by ‘check_time_t_alternatives’ in 2013d.
Here are links to the release files:
https://www.iana.org/time-zones/repository/releases/tzcode2026c.tar.gzhttps://www.iana.org/time-zones/repository/releases/tzdata2026c.tar.gzhttps://www.iana.org/time-zones/repository/releases/tzdb-2026c.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.gzhttps://www.iana.org/time-zones/repository/tzdata-latest.tar.gzhttps://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
71f28b9ab3b67c0f9466803f6151812d4fc8e357 dated 2026-07-08 10:23:58 -0700
and tagged '2026c' in the development GitHub repository at
<https://github.com/eggert/tz>.
Here are the SHA-512 checksums for the release files:
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tzcode2026c.tar.gz
e0b4b7044b66fbc27bc21d13d18063abcdf78ab58d5ba5fd64bd1a88d86e9d495f45add4d8e65bb6c40249f9c94ca29b72c8ebba8d0e4c468f2965ac77932ef0
tzdata2026c.tar.gz
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tzdb-2026c.tar.lz
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