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deps: ICU tzdata needs update to 2026a for America/Vancouver (BC permanent DST) #62323
Description
Version
v25.8.1
Platform
Linux wp10 6.17.0-19-generic #19-Ubuntu SMP PREEMPT_DYNAMIC Fri Mar 6 14:02:58 UTC 2026 x86_64 x86_64 x86_64 GNU/Linux
Subsystem
No response
What steps will reproduce the bug?
British Columbia adopted permanent DST effective November 1, 2026. Node.js currently has America/Vancouver falling back to PST (UTC-8) that day, which will be incorrect. You can verify the bug after November 1, 2026:
node -e "console.log(process.versions.tz)" // shows current tzdata version
node -e "console.log(new Intl.DateTimeFormat('en-CA', {
timeZone: 'America/Vancouver',
timeZoneName: 'short',
year: 'numeric', month: '2-digit', day: '2-digit',
hour: '2-digit', minute: '2-digit'
}).format(new Date('2026-11-01T09:00:00Z')))"
// Expected on patched Node: 2026-11-01, 02:00 PDT
// Actual on unpatched Node: 2026-11-01, 01:00 PST ← wrongRoot cause: The bundled ICU tzdata predates IANA 2026a (released 2026-03-01), which includes the America/Vancouver rule change. Reference: eggert/tz@8b46071
Note also ICU 78.3 mentions updates to timezone data 2026a
Fix: Update deps/icu-small to include tzdata 2026a per the process documented in maintaining-icu.md.
Urgency: The detonation date is November 1, 2026, so there is time, but backports to LTS lines (v22.x, v24.x) will be needed.
How often does it reproduce? Is there a required condition?
Always reproducible, no required conditions
What is the expected behavior? Why is that the expected behavior?
$ node -e "console.log(process.versions.tz)"
2026a
$ node -e "console.log(new Intl.DateTimeFormat('en-CA', {
timeZone: 'America/Vancouver',
timeZoneName: 'short',
year: 'numeric', month: '2-digit', day: '2-digit',
hour: '2-digit', minute: '2-digit'
}).format(new Date('2026-11-01T09:00:00Z')))"
2026-11-01, 02:00 a.m. MST
$
What do you see instead?
$ node -e "console.log(process.versions.tz)"
2025c
$ node -e "console.log(new Intl.DateTimeFormat('en-CA', {
timeZone: 'America/Vancouver',
timeZoneName: 'short',
year: 'numeric', month: '2-digit', day: '2-digit',
hour: '2-digit', minute: '2-digit'
}).format(new Date('2026-11-01T09:00:00Z')))"
2026-11-01, 01:00 a.m. PST
$
Additional information
No response
Activity
richardlau commentedon Mar 18, 2026
This has already been done via #62164. It has yet to go out in a release.
I've run our updater workflow, which has picked up ICU 78.3 and opened #62324. This would have run at the weekend on the usual schedule for the workflow.
albertyw commentedon Mar 27, 2026
tzdata 2026a does not contain updates for America/Vancouver. It contains other changes. The BC DST update will be released in tzdata 2026b or later, discussion in https://lists.iana.org/hyperkitty/list/tz@iana.org/thread/667WE5QTIA7MP2E7NC7T3SO7VLMZLVZS/.
After a new tzdata is released, then it can be incorporated into node through the process @richardlau described.
richardlau commentedon Apr 23, 2026
More info
Our update scripts pull the tzdata from ICU so we'll need them to update first (we don't need an ICU release but the tzdata must be in their upstream repository) before we can update Node.js.
richardlau commentedon Apr 23, 2026
Refs: unicode-org/icu-data#52
richardlau commentedon Apr 23, 2026
We'll also need to watch out for the CLDR wrinkle, and whether that would prevent us being able to take the tzdata without a corresponding ICU update.
mjradwin commentedon May 11, 2026
Looks like this is fixed in Node 26
Pin Node to >=24.15.0 for BC's permanent-DST tzdata fix