The problem in one paragraph
The US moves clocks forward on the second Sunday of March and back on the first Sunday of November. Europe moves on the last Sunday of March and the last Sunday of October. Depending on the year, that leaves three or four weeks when the gap between New York and London is 4 hours instead of 5, and between LA and Berlin is 8 hours instead of 9.
Why it matters for embargoes
If you hand-calculate “09:00 ET is 14:00 GMT”, you will be wrong for those weeks. Anyone who trusts your line publishes an hour early or late. Reporters notice.
The dated collision windows
These are the exact ranges when US and European clocks disagree, computed from IANA timezone data for the current and next year. Use the converter for the exact date rather than relying on a fixed offset.
| Year | Season | From | Until |
|---|---|---|---|
| 2026 | Spring | Sunday, 8 March 2026 | Sunday, 29 March 2026 |
| 2026 | Autumn | Sunday, 25 October 2026 | Sunday, 1 November 2026 |
| 2027 | Spring | Sunday, 14 March 2027 | Sunday, 28 March 2027 |
| 2027 | Autumn | Sunday, 31 October 2027 | Sunday, 7 November 2027 |
- Spring 2026: US on DST, Europe still on winter time. New York to London is 4 hours, LA to Berlin is 8 hours.
- Autumn 2026: Europe off DST, US still on DST. New York to London is 4 hours, LA to Berlin is 8 hours.
How to avoid it
Do not do the math yourself. Use a converter that reads IANA timezone data for the exact date, so “PT” resolves to PST or PDT and “CET” resolves to CET or CEST automatically. That is what the Embargo Timer converter does.
Bonus: countries that do not do DST
Arizona, most of Saskatchewan, Japan, China, India, most of Africa, and every country in the tropics. If your embargo touches any of those, the offset from the US and Europe changes twice a year even if their local time never does.