I am having trouble trying to understand Apple's Timezone Support features.

Taking the following scenario, can anyone explain to me what I can expect to happen with my calendar and alerts:

  1. Timezone support is turned On and set to Central Time for iOS/iCloud.
  2. iPhone > Settings > General > Date & Time > Set Automatically is On
  3. Create an event on my iPhone for 6pm Eastern Time with a 1 Hour Before alert
  4. Travel from Central Time to Eastern Time

What I expect to happen is that, while I am in Central Time, the event will be listed as 5pm, and then automatically change to 6pm when I travel to Eastern Time, alerting me at 5pm.

I am asking this because I have read a lot of articles which make it seem like turning on Timezone Support actually keeps your events listed at the Timezone for which support is set to (i.e. my 6pm Eastern Time event will always show up as 5pm not matter what timezone I travel to because my Timezone support is set to Central Time).

This is all very confusing and I have never fully understood Apple's design intentions with this feature. If anyone can explain to me what's going to happen with my calendar events I would really appreciate it.

1 Answer 1


Time Zone support allows you to view and set events in a time zone other than the one in which you are currently located. The time in which you are viewing events can be set in the time-zone support preference.

Events created whilst time-zone support is off default to the native time-zone of the calendar which was set when it was created and turning time-zone support off lets the iPhone automatically shift the times of appointments to the local time.

A good explanation from apple of the time-zone support can be found here and here.

As for the design rationale, I believe that the confusing naming originates from the development of the feature in iCal. When the feature was built into iCal iCal displayed events in the time-zone of the computer clock which was set manually. Enabling time-zone support permitted "power users" to set the iCal time-zone independently of the computer clock.

If you want your events to act in the way you describe you must disable time-zone support and remember to enter the event times in the local time of the location in which you set it. Alternatively you must enable time-zone support, change to Eastern Time, enter the time of the event and alert in Eastern time, then disable time-zone support.

One thing to note is that time zone support can be simultaniously enabled on your computer and disabled on your phone. If your calendars are synced with iCal this allows you to use the computer to enter the event into the calendar and have it behave as you expect on your phone without mucking around in the settings all the time.

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