Daylight Saving Time and Meeting Scheduling: What Breaks

Why recurring meetings across time zones can silently shift by an hour around daylight saving transitions, and how to avoid it.

A recurring meeting scheduled across two time zones can quietly shift by an hour for one side of the call — not because anyone made a mistake, but because the two regions changed their clocks on different dates.

Why this happens

The U.S. and Europe, for example, both observe daylight saving time, but they start and end it on different dates each spring and fall. For a week or two around each transition, the "gap" between a U.S. city and a European city is briefly one hour different than usual — a meeting that was 3:00 PM their time for months can suddenly land at 2:00 PM or 4:00 PM without either calendar being "wrong."

The fix: time-zone-aware invites, not fixed times

Modern calendar software handles this correctly if a meeting is created with an explicit time zone attached to each participant, since it recalculates the correct local time automatically around each region's own transition dates. The failure mode is a meeting invite sent as a bare time with no time zone context — that one doesn't know to adjust, and it's the most common cause of a recurring meeting quietly landing an hour off twice a year.

Before locking in a recurring meeting, run the exact date through the Time Zone Converter to confirm what each participant's clock will actually say on that day.