[tz-announce] 2026c release of tz code and data available

July 8, 2026

      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.gz
   https://www.iana.org/time-zones/repository/releases/tzdata2026c.tar.gz
   https://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.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 
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:

ad1aadf26b9aaca487a4f780d7a8ebf1d7383472ce587b06cb63852d4eb030dbd190b537e393e75d59530318581e9d3f492ff5f97bbac78f548d0755c4f7257f 
  tzcode2026c.tar.gz
e0b4b7044b66fbc27bc21d13d18063abcdf78ab58d5ba5fd64bd1a88d86e9d495f45add4d8e65bb6c40249f9c94ca29b72c8ebba8d0e4c468f2965ac77932ef0 
  tzdata2026c.tar.gz
3e5aec7d93522efc875fc8af553f78029677aaa9be8db396c862d687bdedb930379ba6246b33a15c5fb3a76d24e937dac4f4f66d6f9edf69a668bb21e9eeada7 
  tzdb-2026c.tar.lz

Here are GPG digital signatures for the release files:

[tz-announce] 2026c release of tz code and data available

Paul Eggert