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

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.

Illustration: Quartz

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.

Illustration: Quartz

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 time. In summer, the same meeting ended at 11 a.m. in New York.

Frankfurt's relationship with London stays fixed. The U.K. changes its clocks on the same Sunday, moving from British Summer Time to GMT at UTC+0. Frankfurt remains one hour ahead of London before and after the switch.

Hubs without daylight saving time see their lead over Frankfurt grow by an hour. Dubai, on UTC+4, is now three hours ahead of Frankfurt rather than two. Tokyo, on UTC+9, goes from seven hours ahead of Frankfurt to eight.

Those gaps between Frankfurt and the Gulf and Asian hubs stay the same when U.S. clocks change a week later.

Illustration: Quartz

Paris moves back to Central European Time, UTC+1, on the last Sunday of October, while New York keeps daylight saving time for seven more days. For that week, Paris sits five hours ahead of New York, not the usual six.

The seven-day spacing is built into the calendar. The Sunday that follows October's last Sunday is, by definition, the first Sunday of November. That is the day the U.S. ends daylight saving time. The two changes can never land in the same week, and they can never sit two weeks apart.

Through the summer, Paris runs on UTC+2 and New York runs on Eastern Daylight Time, UTC-4. That puts six hours between them. Once Paris drops to UTC+1 and New York stays at UTC-4, the distance narrows to five hours. Frankfurt and Zurich, also on Central European Time, make the same move on the same Sunday.

On a clock face, a 3 p.m. call in Paris lands at 10 a.m. in New York during the gap week. The U.S. then switches to Eastern Standard Time, UTC-5. After that, the same 3 p.m. slot in Paris falls at 9 a.m. in New York, and the six-hour gap is back.

The Paris change also moves the city against hubs that never adjust their clocks. Dubai, on UTC+4, goes from two hours ahead of Paris to three. Mumbai, on UTC+5:30, goes from three and a half hours ahead to four and a half. Singapore and Hong Kong, both on UTC+8, go from six hours ahead to seven. Tokyo, on UTC+9, goes from seven hours ahead to eight.

Sydney is already on Australian Eastern Daylight Time, UTC+11. Its clocks stay put this week. Its lead over Paris grows from nine hours to 10.

London changes on the same Sunday as Paris, moving from UTC+1 to UTC+0. The one-hour difference between the two cities holds through the switch.

None of these gaps with Paris changes again when the U.S. falls back a week later. Only the New York figure moves at that point.

Illustration: Quartz

Zurich moves its clocks back on the last Sunday of October, the same day as the EU. For the following week, the Swiss financial center sits five hours ahead of New York instead of the usual six.

Switzerland is not a member of the EU, but it keeps the same daylight saving schedule as its neighbors. Zurich, Frankfurt and Paris leave summer time together. Swiss clocks drop from UTC+2 to Central European Time, which is UTC+1.

New York does not follow until the first Sunday of November. Until then, it stays on Eastern Daylight Time, or UTC-4. That leaves Zurich with a five-hour lead for the whole week.

Once U.S. clocks go back, New York moves to Eastern Standard Time, UTC-5. Zurich's lead returns to six hours, the same gap it holds through the summer.

The difference shows up on any office clock. During the gap week, 5 p.m. in Zurich is noon in New York. While both cities are on summer time, and again after the U.S. change, 5 p.m. in Zurich is 11 a.m. in New York.

The Swiss change also shifts Zurich's position against hubs that never adjust their clocks. Dubai stays on UTC+4 all year. While Zurich is on summer time, Dubai runs two hours ahead of it. After the Swiss change, that gap widens to three hours.

The same pattern holds farther east. Singapore and Hong Kong, both on UTC+8, go from six hours ahead of Zurich to seven. Tokyo, on UTC+9, goes from seven hours ahead to eight.

Zurich's gap with London does not move at all. The U.K. changes on the same Sunday, dropping from British Summer Time to GMT. London stays one hour behind Zurich before and after the switch.

Sydney runs on its own Southern Hemisphere calendar. New South Wales starts daylight saving time on the first Sunday of October, putting Sydney on UTC+11. Before Zurich's change, Sydney is nine hours ahead. During the gap week, it sits 10 hours ahead of Zurich.

Illustration: Quartz

Dubai runs on UTC+4 year-round because the U.A.E. does not use daylight saving time. That puts the city eight hours ahead of New York while Europe has changed its clocks and the U.S. has not. Once U.S. clocks go back, the gap becomes nine hours.

The European changeover does not touch Dubai's gap with New York. New York stays on Eastern Daylight Time, or UTC-4, until the first Sunday of November. Dubai's clocks never move. The eight-hour difference that held through the summer carries straight through the gap week.

What does move this week is Dubai's position relative to Europe. Through the summer, London sits on British Summer Time at UTC+1, three hours behind Dubai. London returns to GMT, or UTC+0, on the last Sunday of October. The gap then widens to four hours. A 9 a.m. start in London now lands at 1 p.m. in Dubai, an hour later than it did the week before.

The same shift applies to the continental hubs. Frankfurt, Paris and Zurich move from summer time at UTC+2 to Central European Time at UTC+1. Their gap with Dubai grows from two hours to three.

The second step comes a week later. The U.S. ends daylight saving time on the first Sunday of November. New York drops to Eastern Standard Time, or UTC-5. Dubai is then nine hours ahead. A 9 a.m. meeting in New York starts at 5 p.m. in Dubai during the gap week. After the U.S. change, the same meeting starts at 6 p.m. in Dubai.

Dubai's gaps with Asian hubs that also skip daylight saving time stay fixed across both weeks. Mumbai, on UTC+5:30, stays an hour and a half ahead of Dubai. Singapore and Hong Kong, both on UTC+8, stay four hours ahead. Tokyo, on UTC+9, stays five hours ahead.

Dubai absorbs two separate one-hour shifts a week apart, first against Europe and then against New York.

Illustration: Quartz

Mumbai stays on UTC+5:30 through the European clock change. India does not use daylight saving time. In the week when Europe has changed and the U.S. has not, Mumbai sits nine and a half hours ahead of New York.

That figure depends on New York's setting. For this week, New York remains on Eastern Daylight Time, or UTC-4. Mumbai sits five and a half hours ahead of UTC. Combined, the two offsets put the cities nine and a half hours apart.

The New York gap does not move when Europe's clocks go back. It moves a week later, when U.S. daylight saving time ends. New York then drops to Eastern Standard Time, or UTC-5. From that point, Mumbai is 10 and a half hours ahead.

The half-hour offset gives the relationship an unusual clock face. When it is 9 a.m. in New York during the gap week, it is 6:30 p.m. in Mumbai. After the U.S. change, the same 9 a.m. start in New York lines up with 7:30 p.m. in Mumbai. Calls between the two cities land on the half hour rather than the hour.

Mumbai's relationship with Europe changes on the earlier Sunday. London moves from British Summer Time, UTC+1, to GMT, UTC+0. Mumbai's lead over London widens from four and a half hours to five and a half hours.

Frankfurt, Paris and Zurich follow the same pattern. They move from summer time, UTC+2, to Central European Time, UTC+1. Mumbai's lead over those three cities grows from three and a half hours to four and a half hours.

A single Mumbai time slot shows the sequence. In summer, 6:30 p.m. in Mumbai is 2 p.m. in London and 9 a.m. in New York. During the gap week, the same Mumbai slot falls at 1 p.m. in London and still 9 a.m. in New York. After the U.S. change, it falls at 1 p.m. in London and 8 a.m. in New York.

None of these shifts starts on Mumbai's side. Each one comes from a clock moving in Europe or the U.S. Mumbai's own offset stays fixed all year.

Illustration: Quartz

Singapore runs on UTC+8 all year and does not use daylight saving time. During the week when Europe has changed its clocks and the U.S. has not, Singapore remains 12 hours ahead of New York. That gap becomes 13 hours once U.S. clocks go back.

The European changeover leaves Singapore's position relative to New York untouched. New York stays on Eastern Daylight Time, or UTC-4, until the first Sunday of November. Singapore's fixed UTC+8 offset sits 12 hours ahead of that. The 12-hour gap that held through the northern summer carries straight through the changeover week.

The shift arrives seven days later. On the first Sunday of November, New York moves to Eastern Standard Time, or UTC-5. Singapore's clocks do not move. The distance between the two cities widens to 13 hours.

Europe is where Singapore sees a difference this week. London leaves British Summer Time, UTC+1, for Greenwich Mean Time, UTC+0, on the last Sunday of October. Singapore goes from seven hours ahead of London to eight hours ahead. Frankfurt, Paris and Zurich drop back to Central European Time, UTC+1. Singapore's lead over those cities grows from six hours to seven.

A Singapore desk working with both regions adjusts in two steps. European counterparts fall an hour further behind on the European changeover Sunday. New York counterparts follow a week later. For one week, only the European side has moved.

The change shows up plainly on the clock. A call set for 4 p.m. in Singapore lands at 8 a.m. in London this week. The week before, it landed at 9 a.m.

The same 4 p.m. Singapore slot reaches Frankfurt, Paris and Zurich at 9 a.m. this week, an hour earlier than before. Singapore's gaps with Tokyo, Mumbai and Sydney hold steady through both changeovers. Tokyo, on UTC+9, stays one hour ahead. Sydney, which switches to Australian Eastern Daylight Time at UTC+11 on the first Sunday of October, stays three hours ahead. Mumbai, on UTC+5:30, stays two and a half hours behind.

Illustration: Quartz

Hong Kong runs 12 hours ahead of New York during the one autumn week when Europe has changed its clocks and the U.S. has not. With a gap of exactly half a day, both cities show the same time on the clock face, one in the morning and the other in the evening.

Hong Kong sits on UTC+8 and does not use daylight saving time. Its clocks stay fixed through the entire autumn sequence. New York remains on Eastern Daylight Time, or UTC-4, until the U.S. change on the first Sunday of November.

The 12-hour gap creates a simple mirror. At 8 a.m. in New York, it is 8 p.m. in Hong Kong. At 6 p.m. in New York, it is 6 a.m. the following day in Hong Kong. Converting times that week only requires swapping a.m. and p.m. For New York afternoons and evenings, the date in Hong Kong also moves forward by one day.

The mirror lasts only one week. Once New York moves to Eastern Standard Time, or UTC-5, Hong Kong sits 13 hours ahead. An 8 a.m. start in New York then falls at 9 p.m. in Hong Kong. A 6 p.m. call in New York lands at 7 a.m. the next day. The swap of a.m. and p.m. no longer works, and every conversion carries an extra hour.

None of that movement starts in Hong Kong. The extra hour comes entirely from the U.S. side.

The European change a week earlier works differently. On that Sunday, Hong Kong's gap with New York does not move at all. Its gap with Europe widens instead. London drops from British Summer Time, UTC+1, to Greenwich Mean Time, UTC+0. That leaves Hong Kong eight hours ahead of London, up from seven. Frankfurt, Paris and Zurich return to Central European Time, UTC+1. That puts Hong Kong seven hours ahead of them rather than six.

Across the two Sundays, Hong Kong's clocks never change, yet its distance from both regions grows by an hour. Europe accounts for the first hour and the U.S. for the second, seven days apart.

Illustration: Quartz

Tokyo is 13 hours ahead of New York in the week between the European and U.S. clock changes. Japan does not use daylight saving time, and Tokyo stays on UTC+9 all year.

That fixed offset means nothing moves in Tokyo when Europe turns its clocks back on the last Sunday of October. New York remains on Eastern Daylight Time, or UTC-4, for that week. The time difference between the two cities holds at 13 hours.

The shift comes a week later. On the first Sunday of November, the U.S. ends daylight saving time and New York drops to Eastern Standard Time, UTC-5. Tokyo's lead then grows to 14 hours, with no change on Japanese clocks.

In practice, a New York morning lands late at night in Tokyo. A 9 a.m. weekday start in New York during the gap week is 10 p.m. the same day in Tokyo. Once U.S. clocks go back, that same New York start falls at 11 p.m. in Tokyo.

The view from Tokyo runs the other way. A 5 p.m. close of the working day in Tokyo equals 4 a.m. in New York during the gap week. After the U.S. change, it equals 3 a.m.

Europe's move does change Tokyo's position against the European hubs. London leaves British Summer Time for GMT, or UTC+0, on that October Sunday. Tokyo's lead over London grows from eight hours in summer to nine hours.

Frankfurt, Paris and Zurich return to Central European Time, UTC+1, on the same day. Tokyo moves from seven hours ahead of those cities to eight hours ahead.

Tokyo's gaps with the other hubs that skip this autumn change stay fixed. Singapore and Hong Kong, also without daylight saving time, remain one hour behind on UTC+8. Dubai, on UTC+4, stays five hours behind, and Mumbai, on UTC+5:30, stays three and a half hours behind. Sydney, already on summer time at UTC+11, stays two hours ahead.