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Clocks went back in Europe but not the U.S.: what it means for 10 business hubs

Clocks go back in Europe a week before the U.S., reshaping time gaps for 10 selected global business hubs, from London and Frankfurt to Tokyo and Sydney

For one week each autumn, the Atlantic gets an hour narrower. Clocks go back in Europe before the U.S. does, on the last Sunday of October. The U.S. keeps daylight saving time until the first Sunday of November. During that stretch, London sits four hours ahead of New York instead of five. Frankfurt, Paris and Zurich sit five hours ahead instead of six.

The mismatch always lasts exactly seven days. The last Sunday of October can only fall between Oct. 25 and Oct. 31. The first Sunday of November can only fall between Nov. 1 and Nov. 7. That calendar arithmetic locks the two changeovers one week apart every year.

Each side of the ocean sets its own rule. EU law fixes the European date, and the U.K. and Switzerland change on the same Sunday. In the U.S., clocks fall back at 2 a.m. local time on the first Sunday of November.

The effect reaches well beyond Europe and North America. Dubai, Mumbai, Singapore, Hong Kong and Tokyo do not use daylight saving time at all. Their clocks stay put through both changeovers. Their distance from London, Frankfurt, Paris and Zurich shrinks by one hour when Europe moves. Their distance from New York grows by one hour a week later, when the U.S. moves.

Sydney runs on a different calendar. New South Wales starts daylight saving time on the first Sunday of October and ends it on the first Sunday of April. Sydney is already on summer time while the Northern Hemisphere is leaving it.

In spring, the order reverses. The U.S. moves its clocks forward first, and Europe follows later. That produces a separate mismatch, not a repeat of this one.

For anyone scheduling calls or chasing deadlines across time zones, this is the week recurring meetings shift. A call pinned to New York time arrives an hour earlier on London clocks than it did the week before.

The 10 hubs below are a selection, not a ranking. Each slide sets out the local time zone, its offset from New York this week and how that offset changes once U.S. clocks fall back.

London switches to GMT and sits 4 hours ahead of New York

London is four hours ahead of New York this week, one hour less than its usual summer gap of five. The U.K. has moved its clocks back to GMT, while New York stays on daylight saving time for seven more days.

Through the summer, London runs on British Summer Time, which is UTC 1. The switch to GMT puts the city on UTC 0. The U.K. makes that change on the last Sunday of October. Countries under EU rules turn their clocks back on the same day.

New York has not moved yet. It remains on Eastern Daylight Time, or UTC-4, until the first Sunday of November.

The shorter gap shows up directly on the clock face. A 9 a.m. call in New York lands at 1 p.m. in London this week. In a normal summer week, it would land at 2 p.m. A London team that signs off at 5 p.m. local time now does so at 1 p.m. in New York, rather than at noon.

The gap returns to five hours once the U.S. leaves daylight saving time. New York then moves to Eastern Standard Time, UTC-5, while London stays on UTC 0.

London's position relative to continental Europe does not change this week. Frankfurt, Paris and Zurich switched to CET, UTC 1, on the same Sunday as the U.K. They remain one hour ahead of London, exactly as they were in summer.

The picture is different for hubs that never change their clocks. Dubai stays on UTC 4, and its lead over London widens from three hours to four. Mumbai, on UTC 5:30, goes from four and a half hours ahead of London to five and a half. Singapore and Hong Kong, both on UTC 8, move from seven hours ahead to eight. Tokyo, on UTC 9, moves from eight hours ahead of London to nine.

Sydney was already on daylight saving time, at UTC 11, when London's clocks went back. It now sits 11 hours ahead of London, up from 10.

Frankfurt on CET runs 5 hours ahead of New York for one week

Frankfurt sits five hours ahead of New York for one week each autumn. That is one hour less than its usual summer gap of six. Germany has returned to standard time, while U.S. clocks stay on daylight saving time until the following Sunday.

The shift follows the EU's clock rule. Under that rule, daylight saving time ends on the last Sunday of October, and Germany changes on that date. Frankfurt moves from summer time at UTC 2 to Central European Time, or CET, at UTC 1.

New York does not move with it. The city stays on Eastern Daylight Time, or UTC-4, until the first Sunday of November. Its clocks fall back seven days after Frankfurt's.

The offsets explain the new gap. Subtracting UTC-4 from UTC 1 leaves five hours. In summer, the same calculation started from UTC 2 and produced six. Once New York falls back to Eastern Standard Time at UTC-5, the six-hour gap returns.

On the clock face, the difference shows up in scheduling. A 9 a.m. call in New York starts at 2 p.m. in Frankfurt during the gap week. Before the European change, the same call began at 3 p.m. local time.

The effect also reaches the end of a Frankfurt working day. A meeting that finishes at 5 p.m. in Frankfurt now wraps up at noon New York........

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