iCloud: Change your calendar’s time zone
By default, your calendars and their events use the time zone set in the Settings app on iCloud.com. You can create events and view calendars in other time zones by turning on time zone support in the Calendar app on iCloud.com. For example, if you’re in the Pacific time zone, time zone support lets you create and view events in the eastern time zone.
If time zone support is on, your calendar events move when you change your iCloud.com time zone in the Settings app. For example, a meeting at 10 a.m. Pacific time in California shows up at 1 p.m. after you fly to New York and change your iCloud.com time zone to eastern time.
If time zone support is off, your calendar events don’t move when you change your iCloud.com time zones. For example, a meeting at 10 a.m. Pacific time in California still appears at 10 a.m. after you fly to New York and change your iCloud.com time zone to eastern time.
Note: Changes you make to the time zone for an event appear on every device that has the iCloud Calendar feature turned on. However, time zone support needs to be turned on individually for each device. For example, if your computer and iPhone have different time zone support settings, the events may show up at different times on these devices.
Use a time zone other than the default
In iCloud Calendar, click the Action pop-up menu in the sidebar, then choose Preferences.
Click Advanced, select “Enable time zone support,” then click Save.
With time zone support on, a Time Zone pop-up menu appears when you create an event, letting you set any time zone you want.