Windows needs its October update before three provinces stop changing clocks

Windows needs its October update before three provinces stop changing clocks

16 October 2026: Manitoba, Alberta and most of British Columbia will not set their clocks back an hour on 1 November, and Windows only knows that once the October cumulative update is installed and a new region-specific time zone is selected. Microsoft has told Microsoft 365 administrators that devices without both will show the wrong local time from the transition onwards, which also shifts meetings booked across the change.

Not yet independently verified. The provincial decisions are described here as Microsoft's own posts state them. We have not yet read the three provincial governments' announcements, and will add them as sources once we have. We will update this when it can be confirmed, and remove this note.

Three provinces, three new offsets

Microsoft's posts set out what each province decided. Manitoba announced on 17 September that it will remain permanently on UTC-5. Alberta announced in June that it will stay on UTC-6, and British Columbia announced in March that it will stay on UTC-7. In each case the clocks simply do not fall back at 02:00 on 1 November.

The Alberta change also covers Yellowknife and Inuvik in the Northwest Territories and the communities in south-eastern British Columbia that keep Alberta's time. To carry the change, Windows gains three new entries rather than altering the existing ones:

• (UTC-05:00) Manitoba
• (UTC-06:00) Mountain Time (Alberta)
• (UTC-07:00) Pacific Time (British Columbia)

That design matters for fleet owners. Devices set to choose their time zone automatically move to the new entry on their own, but any machine where the zone was set by hand, by image or by policy keeps the old "Central", "Mountain" or "Pacific" entry, which will still fall back an hour.

Which updates carry the change

The Alberta and British Columbia rules first shipped in the September non-security preview for Windows 11 versions 25H2 and 24H2. Every other supported version, including Windows Server, received them in the October security update, which is also the release that brought Manitoba to all supported versions. The knowledge base articles Microsoft lists are:

• Windows 11, versions 25H2 and 24H2: KB5124010 (preview) and KB5127648 (October security update)
• Windows 11, version 23H2: KB5126653
• Windows Server 2025: KB5126646
• Windows Server 2022: KB5126655
• Windows 10 Enterprise LTSC 2021: KB5126657
• Windows Server 2019: KB5126651
• Windows Server 2016: KB5126868

Microsoft added guidance for Outlook to its notice the same day, because calendar items created before the change can carry the old offset and appear an hour out once the provinces stop changing.

Stopgaps for machines that miss the update

For devices that cannot take the update before 1 November, Microsoft publishes fixed-offset workarounds and is clear that they are temporary, because the substitute zones have different names, mappings and historical rules. Alberta devices can move to (UTC-06:00) Saskatchewan after the transition and British Columbia devices to (UTC-07:00) Yukon. Manitoba is the awkward one: the suggested substitute is Eastern Time with automatic daylight saving turned off, which Microsoft says can be applied before the transition because Manitoba is already on UTC-5 until then, and must be switched back once the update is in.

Servers deserve the same attention as laptops. Scheduled tasks, log timestamps and anything that converts local time for customers in those provinces will drift by an hour on systems still on the old rules. We list Microsoft as a company, and our patch management software category lists seven products that can report which machines still lack the October update.

Sources

• Microsoft 365 Message Center MC1510951: Windows updates are available for 2026 time zone changes in Canada (archive copy), 16 October 2026
• Microsoft Daylight Saving Time & Time Zone Blog: Manitoba 2026 time zone update available now, 14 October 2026
• Microsoft Daylight Saving Time & Time Zone Blog: Alberta 2026 time zone update available now, 14 October 2026
• Microsoft Daylight Saving Time & Time Zone Blog: British Columbia 2026 time zone update available now, 14 October 2026
• Microsoft Support: Outlook time zone changes for Alberta and British Columbia (read 2026-10-17), 17 October 2026