The short answer: a recurring cross-border meeting shifts by an hour because the two countries changed their clocks on different dates — or one observes daylight saving and the other does not. For the roughly three-week window between the two changes, the offset between the cities is temporarily an hour different, so the call appears to move. Once both sides have changed, it lines up again.
Nothing is broken. Your calendar did exactly what it was told. The problem is that the gap between two countries is not a fixed number — it breathes by an hour twice a year, and the two sides rarely breathe in sync.
Why does the meeting move at all?
A recurring event is stored in one time zone and converted for everyone else. As long as the gap between two cities stays constant, the converted times stay put. But daylight saving changes that gap. When one country springs forward and the other has not yet done so, the distance between them grows or shrinks by an hour. Your meeting did not move; the world around it did.
Why does it only last a few weeks?
This is the tell-tale sign. The United States, the United Kingdom and the European Union all change clocks on different dates, usually within a three-week window of each other in spring and again in autumn. During that gap the offset is off by an hour. Once the slower side catches up, the normal gap returns and the meeting snaps back to its usual time.
So if a long-running call suddenly drifts in mid-March or late October and then quietly corrects itself a couple of weeks later, daylight saving is almost certainly the cause. For the exact change dates, see our guide to daylight saving dates in 2026.
How do I diagnose it?
Work through these in order. One of them will explain almost every case:
- Has one side just changed its clocks? Check whether either country entered or left daylight saving in the last three weeks. If one has and the other has not, you have found it.
- Does one side observe DST at all? Some countries never change their clocks. A call between, say, a DST country and a non-DST one will shift twice a year, every year, like clockwork.
- Which zone is the series anchored to? Open the recurring event and look at its time zone. If it is anchored to a DST zone, attendees in a non-DST zone will see the local start time move when the anchor changes.
| What you see | Likely cause |
|---|---|
| Shift in mid-March or late October, self-corrects | Clocks changed on different dates |
| Shifts twice a year, every year | One side does not observe DST |
| Only some attendees see the new time | Series anchored to one zone, others converted |
| Permanent shift, never corrects | A region changed its DST law, not a one-off |
How do I fix it for good?
There are three reliable approaches, from quickest to most robust:
- Anchor the series to one zone deliberately. Pick the zone of whoever the meeting matters most for and let the calendar convert for everyone else. The anchor's local time stays fixed; the others adjust automatically.
- Re-check around the clock changes. Put a note in your own calendar for the spring and autumn change weekends to confirm the call still suits everyone. A two-minute check beats a missed meeting.
- Schedule with a tool that knows each attendee's DST rules. The cleanest fix is to never guess at all: store each person's actual zone, with its daylight saving rules, and let the software do the conversion.
Rather than doing the offset arithmetic in your head, read each person's real local time before you commit a recurring slot. For a deeper look at why these calls drift in the first place, see recurring meetings and daylight saving.
How Atlas handles it
Atlas pins each teammate or city on a world map with their live local time and stores their zone with its daylight saving rules. When you find a slot, it does not just show the overlap — it suggests the best moment and adds the meeting to your calendar in everyone's correct local time, with daylight saving already handled. A keyboard shortcut summons a Quick Check whenever you need to glance at the gap. Because the zones carry their own DST rules, a recurring slot you book stays right through the spring and autumn changes, without you having to remember the dates.
Frequently asked
Why did my recurring meeting move by an hour?
Why does the shift last only a few weeks?
How do I stop a recurring meeting from drifting?
Does it matter which time zone I create the meeting in?
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