Apple Calendar events one hour late from Alberta time zone.

Question

Apple Calendar events one hour late from Alberta time zone.

Alberta Permanent Time Zone Change (Nov 1, 2026) Causing Recurring Calendar Events to Display One Hour Late on Apple Devices

We're seeing what appears to be a widespread issue affecting recurring calendar events on Apple devices following Alberta's move to a permanent UTC-6 time zone effective November 1, 2026.

What we're seeing

We have been able to consistently reproduce the issue in our environment.

Recurring meetings that were created before the time zone change display correctly in Outlook on the Web (OWA) and Outlook for Windows.
The same meetings display one hour later than expected on some iPhones, iPads, and Macs after November 1, 2026.
The issue affects Apple's native Calendar app and, in some cases, the Outlook mobile app on iOS as well.
Non-Apple platforms appear to show the correct meeting times.

Example

A recurring meeting scheduled for 8:00 AM daily continues to display as 8:00 AM in:

Outlook on the Web (OWA)
Outlook for Windows

However, after November 1, the same meeting appears as 9:00 AM on affected Apple devices.

Troubleshooting already performed

We've tested the common recommendations, including:

Updating devices to the latest available OS versions
Verifying automatic date and time settings
Verifying location services and time zone settings
Recreating calendar profiles/accounts
Comparing behavior across multiple Apple devices

The issue persists.

Suspected cause

Based on our testing, it appears Apple devices may not yet be fully recognizing Alberta's new permanent time zone rules after November 1, 2026.

Because Outlook on Windows and Outlook on the Web display the correct time, it does not appear that the calendar data itself is incorrect. Instead, the issue seems to be related to how certain Apple devices or applications are interpreting Alberta's time zone information when calculating future occurrences of recurring events.

Questions for the community

Has anyone else in Alberta reproduced this issue?
Are you seeing it in Apple Calendar, Outlook for iOS, or both?
Are there any confirmed workarounds besides viewing calendars in OWA or Outlook for Windows?
Has Apple acknowledged any pending update to address Alberta's permanent UTC-6 time zone change?

Any feedback would be appreciated. We're trying to determine whether this is an isolated issue or something that may affect a larger number of Alberta users as November approaches.

Thanks!

Posted on Sep 29, 2026 7:41 AM

Reply

Answer 1

Top-ranking reply

MocoLoco88

Level 1

18 points

Oct 5, 2026 9:18 AM in response to jhallegallais

I believe that the problem you're describing is actually the opposite, which is that Apple's devices are recognizing the new Alberta time zone, whereas your Outlook/Windows configuration has not yet updated to the new time zone and there is a larger calendar update problem with Microsoft. Most likely, your calendar entry displays in Outlook with the same time because your Outlook/Windows configuration has not been updated, and therefore the systems aren't making Alberta specific adjustments yet. Our observations in our environment are as follows:

In order to make available and change to the new "Mountain Time (Alberta)" zone within Windows, you must apply the latest Windows update and this may not be automatic. Specifically, September 22, 2026—KB5124010 (OS Builds 26300.9550, 26200.9550, and 26100.9550) Preview | Microsoft Support .
If your time zone is set to automatically update, then your time zone in Windows will be set to "Mountain Time (Alberta)". If it is not set to automatically update, then this will now be an available option in the pulldown and you can set it as such.
As it relates to Outlook, you must also change the time zone settings within Outlook as well, as this is separate from the OS setting.
For all existing Outlook calendar entries that you own, the problem is that when they were created originally, no Alberta time zone existed at that time, and therefore they would most likely have been created in the "Mountain Time (US&Canada)" zone. Your calendar entries are encoded with that time zone.
For devices that recognize and have changed to Alberta time (i.e. your iPhones, or Windows/Outlook after you apply the updates), if the programming sees an entry past November 1 with a time zone of "Mountain Time (US&Canada)", which is still a correct and valid time zone with daylight savings time adjustments, then it will change the time reflected on your calendar to Alberta time, which is obviously 1 hour offset.
Unfortunately, Microsoft has not made any mechanism or tool to detect that you are in Alberta, and that all your calendar entries should remain the same in local time, which would be the logical action (i.e. your meeting that you created at 2pm Mountain Time (US&Canada) should remain at 2pm Mountain Time (Alberta)).
It follows from this that all users must change their calendar entries manually to Mountain Time (Alberta) past Nov. 1. This is confirmed in the latest Microsoft guidance: Outlook Time Zone Changes for Alberta and British Columbia | Microsoft Support .

In short, I believe Apple devices are not the problem here, but yes, this does affect a large number of Alberta users, and there will be a lot of impact/remediation.

Reply

Answer 2

Oct 5, 2026 11:33 AM in response to MocoLoco88

Thank you for the detailed reply and for sharing Microsoft's guidance.

After reviewing my setup further, I changed the time zone in Outlook to Mountain Time (Alberta) (UTC-06:00) and allowed everything to sync.

What I noticed is that the calendar entries displayed within the Outlook app on my iPhone now show the correct times. However, when I view the same Microsoft 365 calendar through the native Apple Calendar app (with my Microsoft account synced), the events still appear one hour ahead.

Before I changed my time zone, both the Outlook app on my iPhone and the native Apple Calendar app were 1 hour off, so we've made some progress.

Based on that testing, it appears that Outlook is now correctly interpreting the Alberta time zone, while the native Apple Calendar app is still displaying these existing appointments with a one-hour offset. As a result, the Outlook app is currently the only calendar source on my iPhone that I can reliably trust for accurate appointment times.

I appreciate the information regarding Microsoft's handling of existing calendar items and the need to review appointments created before the Alberta time zone change. At this point, though, my observations suggest that the remaining discrepancy I'm seeing is specific to how the native Apple Calendar app is displaying the synced Outlook events.

Thanks again for taking the time to look into this and provide the background information

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Answer 3

Zifnab0

Level 1

8 points

Oct 22, 2026 10:10 AM in response to jhallegallais

I am also seeing this issue in British Columbia. Specifically with recurring meetings synchronized from Outlook to the iPhone calendar that cross over November 1. These meetings are shifted ahead an hour in the iPhone calendar after November 1.

In Outlook my time zone is set to '(UTC-07:00) Pacific Time (British Columbia)'. My iPhone has set time zone automatically enabled and has set me to Mountain Standard Time/Creston which is also UTC-7:00.

Scenario 1: I create a recurring meeting in the iPhone calendar crossing over November 1 at 6:00pm on Friday.

This event shows as 6:00pm Friday before and after November 1 in the iPhone calendar as expected.
This event shows at 6:00pm Friday in Outlook calendar before and after November 1 which is correct. If I look at the details on the event in Outlook it shows the time zone as '(UTC-07:00) Arizona'.

Scenario 2: I create a recurring meeting in Outlook calendar that crosses over November 1 at 6:00pm on Friday.

This event shows up at 6:00pm Friday before and after November 1 in the Outlook calendar as expected. In the event details the time zone in Outlooks is '(UTC-07:00) Pacific Time (British Columbia)'
This event shows at 6:00pm Friday before November 1, but at 7:00pm Friday after November 1 in the iPhone calendar. When I look at the event in the iPhone calendar it shows '6 pm - 6:30 pm (PST)'.

I agree with the suspected cause above. When the event syncs from Outlook to the iPhone calendar using the new time zone in Outlook the time zone for the event is set to PST which causes the offset problem after November 1.

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Answer 4

RAllanR

Level 1

8 points

Oct 15, 2026 9:37 PM in response to jhallegallais

For what it's worth I've run into a similar situation although not as complex as yours.

I recently booked a flight from Victoria, BC to Toronto. On my iPhone the flight shows correctly using PDT as the departure and EST as the arrival time zones. And reflects the soon to be in place 2 hour time difference between Victoria and Toronto once Ontario "falls back" to standard time. However the Calendar app on my Mac laptop shows PST and EST as the time zones meaning the departure time in Victoria is one hour off as it's not accounting for the new 2 hour difference and still thinks there will be a 3 hour one. For some reason the iPhone understands the change but the laptop calendar doesn't.

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Answer 5

Oct 21, 2026 7:06 AM in response to MocoLoco88

My experience proves otherwise. This issue it not isolated to Microsoft only. Events created in Google Calendar exhibit same behavior on iOS

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