Apple Calendar events one hour late from Alberta time zone.

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:

1. 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 .
2. 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.
3. 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.
4. 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.
5. 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.
6. 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)).
7. 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.

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

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.

The original poster is absolutely correct. Microsoft applications are working (for example, my Teams calendar in the Teams app is correct) but the native Apple calendar app is off by 1 hour. I have updated the iOS and restarted my phone, as per any instructions I could find online. Nothing has worked; with 6 days left until November, I'm not optimistic there will be resolution in time. As I'm in Alberta, as of November I will be changing my phone to reflect Saskatchewan time.

I will say… now that my Outlook has been updated (thanks to a tool provided by UBC which was shared with my own institution) my calendar has been fixed. I’ve not had to do a thing to my phone, but my Apple calendar syncs to my outlook calendar so all good. A few things that I’d entered on the Apple calendar I was able to fix in outlook, but fortunately my outlook calendar adjustment took care of most things. No thanks to Apple, but at least on my end the situation seems to be resolved.

Same problem for Manitoba. Calendar events displaying 1 hour behind. IOS has recently been updated and did not correct the problem. There isn’t any update for the calendar in the App Store.

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.

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

I am also having this issue and changing settings around calendar timezones does not seem to hold - I change them from automatic to override and it appears to work, then the next day it is off again, so I change it back. Still off. Even events I’ve changed time zones directly in are off. This is so frustrating. Posting here in case a fix shows up.

I have the same problem. My calendar events in Outlook and OWA using the correct timezone for BC, but the iOS Calendar still marks them as being in PST, which causes them to be out by an hour, rather than PCT.

I am in Manitoba and I am having the same problem. Anything I had imputed in my calendar is a hour later than it is intended. I’ve tried doing time zone over ride, updates, turning off and on. It hasn’t changed.

It’s not just Alberta affected but also BC. One cannot change to “PT” or British Columbia as it requires specific city so I am unable to fix the problem for Vancouver either

I am in Manitoba and am having this problem as well, but this is happening in the apple calendar app for me. As of Nov 1, every event in my calendar is off by 1 hour (recurring events and on-time events).

In addition, it appears that the Set Timezone Automatically and Set Time Automatically options are inaccessible. My device has updated to central time in Saskatchewan even though I am in Alberta and it won’t allow me to change it.

I have done all of these steps on my calendar.

We originally booked meeting in Mountain Tim (UTC-7). We updated computers, OWA settings and all meeting time zones

They are now set to UTC-6 (Alberta). Meetings in outlook seem to update time, but apple native calendar is showing the meetings an hour late.

Does it have something to do with automatic time zone settings?

Now that it's happening to all of us, is there going to be a fix? I've tried everything suggested everywhere, and my subscribed calendars (TeamSnap) are coming in an hour later than they should be. I have no option for "Alberta Time".

Please fix this!! I am in Alberta and I create my personal appointments in my Apple calendar but send an invite to my work calendar (which is in Outlook). In the calendar app I use Calgary, Canada Mountain Daylight Time to create the event but when it arrives in Outlook it shows as an hour later. Somewhere in between there is a bust as Outlook has the time zone as Mountain Time (Alberta) which was newly created.

My Apple calendar is showing 1 hour earlier for November. It is not recognizing the permanent change to DST but falling back 1 hr to MST. My 9:30am DST appointment is showing as 8:30am.

Same issue here for me in Alberta, when will this be fixed?

Me again. So November/December is showing correctly. But appointments in the new year aren’t? Make the madness end! Lol