The three weeks a year the US and Europe are out of step
The US springs forward in March. Europe waits. In between, every transatlantic recurring call is an hour off from what both calendars claim.
The short answer
The US changes on 2026-03-08; the EU waits until 2026-03-29. For the three weeks between, the transatlantic gap is four hours instead of five.
It happens again in autumn, shorter and reversed: Europe falls back on 2026-10-25, the US on 2026-11-01.
The two windows
| Window | Who has moved | New York ↔ London |
|---|---|---|
| Before 2026-03-08 | Neither | 5 hours |
| 2026-03-08 – 2026-03-29 | US only | 4 hours |
| 2026-03-29 – 2026-10-25 | Both | 5 hours |
| 2026-10-25 – 2026-11-01 | Europe only | 4 hours |
| After 2026-11-01 | Neither | 5 hours |
Three of the five rows are the ordinary five hours. The other two are the gap weeks — about three weeks in spring, about one in autumn.
Why the dates differ
There is no deep reason. The two regions legislated separately and picked different rules.
- United States: Energy Policy Act of 2005 — second Sunday in March to first Sunday in November, switching at 02:00 local.
- European Union: Directive 2000/84/EC — last Sunday in March to last Sunday in October, switching simultaneously at 01:00 UTC.
The US extended its daylight saving period in 2007, which widened the spring gap from one week to three. Before that, the mismatch was small enough that most people never noticed it.
The EU voted in 2019 to abolish the twice-yearly change entirely, but member states never agreed on which time to settle on, and the directive remains in force. So this is not going away soon.
What it breaks, concretely
Recurring calendar invites written as fixed local times on both sides. The invite does not change; the offset under it does. The meeting happens an hour earlier for half the attendees, for three weeks, then corrects itself — which is why it is so rarely diagnosed.
Anything scheduled through the window. A date agreed in February for early April, computed by hand at five hours, is an hour wrong if it lands in the gap.
Automated reports and cron jobs that assume a constant five-hour relationship. They produce output an hour early or late, usually noticed only when two logs are reconciled.
On-call rotations defined in local time on both sides can gain an hour of double coverage — or, worse, lose an hour where nobody holds the pager.
The fix
Schedule against cities. A calendar event created with a zone attached resolves through the tz database, which encodes both regions' rules, including the gap weeks. It will be right without anybody thinking about it.
Define machine schedules in UTC. UTC has no transitions.
Diary the four dates. 2026-03-08, 2026-03-29, 2026-10-25, 2026-11-01. Those are the only moments a standing transatlantic arrangement can move.
Related: Eastern Time to GMT · For three weeks a year the US and Europe are out of step
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Figures on this page are computed from the IANA time zone database. Last generated 2026-08-18.