In order to address time zone changes, this tool will help adjust calendar items in Outlook after the operating system has been updated with new time zone definitions. This tool can be used for general adjustments of calendar items based on changes in time zone definitions saved in Windows or by the user making a permanent move to another time zone. Version 3 addresses several issues reported by customers while using the previous version of the tool. It also allows to access the tool via the Microsoft Windows Start menu.

Specifics:
In existing recurring appointments, Outlook has encoded the current DST rules. Instances of recurring appointments that occur during the delta period will appear one hour earlier than they should.
For existing single-instance appointments and reminders, Outlook already calculated the universal time coordinate (UTC) value upon appointment creation: If a user creates an appointment while Windows is configured for the old DST rules and the appointment itself occurs during the "new" DST weeks, the appointment will appear one hour earlier than it should.
Existing all-day events are associated with 24 specific hours instead of a given date: For the reasons described above, all-day events will appear to shift and thus span two days during the "new" DST weeks.

For addtional information about the time zone changes and Microsoft Office Outlook, refer to the Addressing daylight saving time using the Outlook Time Zone Data Update Tool Support article.