On 2026-07-16 12:58, Matt Johnson-Pint wrote:
I don't see any mention of Canadian changes on their blog yet. I suspect they could be waiting to see if the US aligns or not, to reduce the required work.
As I understand it, Microsoft aims to distribute patches within about twelve weeks of a government announcement of timekeeping rule changes; see Farhan Ali's 2023 blog post[1]. Ali mentions as an example the spring 2022 changes for Chile, announced August 8 and affecting timestamps starting September 11. In that year, TZDB issued a new release August 10 and Microsoft issued a patch October 11, within their twelve-week target but too late for the actual timekeeping change.
The British Columbia changes this year are a bigger deal, as they're not simply a rule change but a time zone and nomenclature change. Although BC announced them on March 2, TZDB 2026b wasn't released until April 22, partly because of the issue of accommodating issues of CLDR downstream. And although faster Linux distros like Arch published tzdata updates in a few hours or days after April 22, more-cautious distros weren't updated until weeks later: Ubuntu, for example, was not updated until July 8.
Given the BC updates' severity (plus the alignment issues you mention), it's not surprising that Microsoft has taken longer than its 12-week goal. For Alberta (which announced June 18), Microsoft's 12-week target date would be September 10; if Microsoft has merged BC and Alberta perhaps they'll put out patches for both around then.
Keep an eye on http://aka.ms/dstblog for official details.
Thanks for the pointer. I installed the attached patch to link to that blog.[1]: https://techcommunity.microsoft.com/blog/windows-itpro-blog/how-windows-manages-time-zone-changes/3852632
From 93f11af35c7ddb27e925e09ade6d4918f4f271bc Mon Sep 17 00:00:00 2001 From: Paul Eggert <[email protected]> Date: Thu, 16 Jul 2026 14:04:58 -0700 Subject: [PROPOSED] =?UTF-8?q?Microsoft=E2=80=99s=20Daylight=20Saving=20Ti?= =?UTF-8?q?me=20&=20Time=20Zone=20Blog?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit * zone.tab: Mention the blog. (Thanks to Matt Johnson-Pint.) --- tz-link.html | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/tz-link.html b/tz-link.html index 2a7da95e..7da83fa5 100644 --- a/tz-link.html +++ b/tz-link.html @@ -684,7 +684,10 @@ data (mentioned <a href="#CLDR">below</a>) used by the <a href="https://en.wikipedia.org/wiki/Windows_Runtime";>Windows Runtime</a> / <a href="https://en.wikipedia.org/wiki/Universal_Windows_Platform";>Universal Windows Platform</a> classes <a href="https://learn.microsoft.com/en-us/uwp/api/Windows.Globalization.DateTimeFormatting.DateTimeFormatter";><code>DateTimeFormatter</code></a> and -<a href="https://learn.microsoft.com/en-us/uwp/api/windows.globalization.calendar";><code>Calendar</code></a>. +<a href="https://learn.microsoft.com/en-us/uwp/api/windows.globalization.calendar";><code>Calendar</code></a>, +and with updates discussed in the +<a href="https://techcommunity.microsoft.com/category/windows/blog/dstblog";>Daylight +Saving Time & Time Zone Blog</a>. <a id="System.TimeZoneInfo" href="https://learn.microsoft.com/en-us/archive/blogs/bclteam/exploring-windows-time-zones-with-system-timezoneinfo-josh-free";>Exploring Windows Time Zones with <code>System.TimeZoneInfo</code></a> describes -- 2.53.0
