To: Time zone announcements <[email protected]>
Subject: 2026d release of tz code and data available
The 2026d release of the tz code and data is available. This release is
prompted by the decision of the Northwest Territories to stay on permanent
UTC-06, which has a practical effect starting 2026-11-01 at 02:00. Like the
similar changes for Alberta and British Columbia in the previous two tzdata
releases, there will likely be problems downstream as CLDR’s latest release
cannot handle it as specified.[
This release contains the following changes:
Briefly:
Canada’s Northwest Territories moved to permanent -06 on 2026-08-21.
Obsolescent settings like TZ="EST5EDT" now conform better to POSIX.
Fix security, performance and porting bugs in zic and localtime.
Changes to future timestamps
Canada’s Northwest Territories will not fall back on 2026-11-01
and will stay on -06 year-round, matching Alberta’s recent change.
Model this with its traditional abbreviation CST. Although the
change to permanent -06 legally took place on 2026-08-21,
temporarily model the change to occur on 2026-11-01 at 02:00
for the same reason as other recent temporary hacks. (Caution:
see “NOTE FOR 2026b TEMPORARY HACK FOR CLDR AND CANADA” below.)
This affects only America/Inuvik as the rest of the territory is
covered by America/Edmonton, for which the equivalent change was
released in 2026c.
NOTE FOR 2026b TEMPORARY HACK FOR CLDR AND CANADA:
This zic fix is needed for the temporary hack (mentioned above)
that works around the Canadian timekeeping bug in Unicode CLDR.
Without the fix, the temporary hack causes zic versions 2023d
through 2026a, in their default mode that generates slim output,
to generate a TZif file that violates Internet RFC 9636 §3.3.
The buggy file in turn causes some TZif readers, including tzcode
itself, to ignore America/Vancouver’s 2026-11-01 02:00 transition
from PDT (tm_isdst=1) to MST (tm_isdst=0). Although the buggy
file does not cause any known TZif reader to mishandle UT offsets,
caution is advised when using zic 2023d through 2026a to compile
data from more-recent tz releases. To work around this problem
when using these older zic versions, use ‘zic -b fat’.
Changes to past timestamps
Colombia’s 1992-05-02 spring forward was at 00:00, not 24:00.
Iran’s 1979-05-26 spring forward was at 00:00, not 24:00.
(Thanks to N.F. Hase.)
The backward-compatibility names EST5EDT, CST6CDT, MST7MDT, and
PST8PDT now conform better to POSIX. For example, EST5EDT now
always uses the abbreviation "EST" for standard time (now always 5
hours behind UT) and "EDT" for daylight saving time, whereas it
formerly had different UT offsets before standard time was
introduced and sometimes used abbreviations like "LMT", "EWT" and
"EPT", all contrary to POSIX. Also, though not required by POSIX
these names now use US federal rules rather than rules of places
like New York, reverting to 2024a behavior. This change affects
only timestamps before 1966-10-30 at 01:00 standard time.
Other data changes
The temporary hacks used for North American timekeeping changes
now work around a libstdc++ std::chrono bug in GCC 14.1-14.4,
15.1-15.2, and 16.1; see GCC bug 124851. This data change does
not affect TZif files or timestamps. The change does not work
around the related but less serious GCC bugs 116110 and 124513.
These GCC bugs are all fixed in GCC 16.2.
Changes to code
zic now rejects Link targets that would have invalid names, and
more efficiently processes Expires, Leap and Rule lines with years
far in the past or future. (Thanks to Darren Carreras.)
zic now ports to systems that report lack of link support via
EINVAL, ENOSYS or EPERM errno values. (Thanks to Tom Lane.)
When tzset and related functions encounter a TZif file that is too
large for them, they now consistently fail instead of sometimes
silently ignoring excess parts of the file.
localtime-related functions no longer mishandle extreme timestamps
when given TZif files holding some unlikely timezone histories.
(Problem reported by David Sarkisyan.)
localtime-related functions no longer check the values of TZif
files’ standard/wall and UT/local indicators, which these
functions have not used since 2026a’s removal of the old
posixrules feature.
tzcode has been ported to Haiku.
localtime.c now works again by default on AIX and DragonFly BSD.
zic now rejects ‘:’ and ‘\’ in Zone and Link names when running on
Microsoft Windows. (Problem reported by David Diaz.)
Changes to documentation
URLs for release tarballs in tz-link.html have been updated to
reflect their new canonical URLs on data.iana.org.
Here are links to the release files:
https://www.iana.org/time-zones/repository/releases/tzcode2026d.tar.gz
https://www.iana.org/time-zones/repository/releases/tzdata2026d.tar.gz
https://www.iana.org/time-zones/repository/releases/tzdb-2026d.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 d633fe7ed3de8e00ce7cac991376a064a1373bb1 dated
2026-09-11 15:21:07 -0700 and tagged '2026d' 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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tzcode2026d.tar.gz
1a27de5af50bbc28a2f64c506ab3678b09d9e5ab6c118f39eb38bb823aa8f57069bf5e465848e71df8274c6b8bcd0fc736a88107e5792d816a1db5d867cbc219
tzdata2026d.tar.gz
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tzdb-2026d.tar.lz
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