The DST mismatch weeks of 2027: when the US, Europe and Australia are out of sync

The short answer

In 2027 New York is 4 hours behind London instead of 5 twice: from 14 to 28 March (two weeks) and from 31 October to 7 November (one week). The same windows shorten every U.S.–Europe gap by an hour.

Across the hemispheres the gaps move further. London–Sydney passes through 11, 10 and 9 hours during the year, and New York–Sydney through 16, 15 and 14. Sydney and Auckland, normally 2 hours apart, are 3 hours apart for one week from 26 September.

A recurring meeting stays at the same local time for whoever owns the invite and moves by an hour for everyone else during these windows. Every date and offset below was computed from the IANA time zone database (tzdata 2026e, via Node.js 22.23.4).

The 2027 clock changes

Each U.S. zone changes at 02:00 local time, so the UTC instant is an hour later per zone going west: 07:00 UTC in New York, 10:00 UTC in Los Angeles. Europe does the opposite: every EU country changes at the same UTC instant, which is 02:00 in Berlin and 03:00 in Athens. Adelaide changes at the same local times as Sydney, so half an hour later in UTC.

The legal rules: the U.S. dates come from the Energy Policy Act of 2005, the EU's from Directive 2000/84/EC, the UK's from the Summer Time Order 2002, Australia's from each state and territory, and New Zealand's from its daylight saving rules. Chile's dates are as recorded in the tz southamerica data file.

No change in 2027: Queensland (Brisbane, UTC+10), Western Australia (Perth, UTC+8), the Northern Territory (Darwin, UTC+9:30), Arizona except the Navajo Nation (UTC−7), Hawaii, Japan, India, China, Brazil, Paraguay, Morocco and Magallanes and Aysén in southern Chile. Mexico has not changed clocks since 2022 outside the northern border municipalities, which follow the U.S. dates (Ley de los Husos Horarios): Mexico City stays on UTC−6 all year. From November 2026, British Columbia, Alberta, the Northwest Territories and Manitoba also stopped changing (what changed in 2026).

The mismatch windows, pair by pair

Gaps on 15 January and 15 July, and the windows when the gap takes a third value because only one side has changed:

Each window starts and ends at the UTC instants in the first table. New York–London, for example, is 4 hours from 07:00 UTC on 14 March to 01:00 UTC on 28 March.

Two details the table hides:

• The spring transatlantic window is two or three weeks, the autumn one always one week. The U.S. moves on the second Sunday of March and Europe on the last, which is 14 or 21 days later depending on the calendar. In 2026 it was three weeks (8 to 29 March); in 2027, 2028 and 2029 it is two. In autumn Europe moves on the last Sunday of October and the U.S. on the first Sunday of November, which is always exactly seven days later.
• Sydney and Auckland are only 1 hour apart for two hours on 4 April. New Zealand falls back at 14:00 UTC and New South Wales at 16:00 UTC. It only matters to systems running jobs at that hour.

Brisbane and Sydney are not a mismatch but a seasonal change: same time from 4 April to 3 October, 1 hour apart the rest of the year, because Queensland does not observe DST.

North America has new seasonal gaps

From November 2026 western Canada stopped changing its clocks while its neighbours did not. That creates gaps that change twice a year, every year, between cities that used to move together:

These are not week-long windows. They last four to eight months, so they affect more meetings than the transatlantic weeks do. Mexico City has worked this way since 2022.

What it does to a recurring meeting

A weekly 11:00 New York meeting is at 16:00 in London and 17:00 in Berlin for most of the year. On the meetings between 14 and 27 March and between 31 October and 6 November it is at 15:00 in London and 16:00 in Berlin.

A weekly 08:00 London meeting with Sydney and Auckland changes four times for each of them:

A weekly 09:00 New York meeting with Santiago, Mexico City and Vancouver is 11:00, 08:00 and 07:00 there in January. Between 4 April and 4 September it is 09:00, 07:00 and 06:00.

How to schedule around the windows

1. Pin each series to one named zone and say which. Write "every Monday 11:00 America/New_York" in the description. The owner's zone is the one that never moves, so pick the owner on purpose: the person with the least flexible day, or the side with the most attendees.
2. Choose a slot with an hour of slack on both sides. New York–London is forgiving: a 10:00 or 11:00 New York meeting stays inside London's working day at either gap. Cross-hemisphere pairs are not: the gap moves by two hours over the year, so a London–Sydney slot that suits Sydney in January lands two hours earlier for Sydney in July.
3. Put the windows in the calendar now. For a U.S.–Europe team, mark 14–28 March and 31 October – 7 November 2027. For Australia or New Zealand, add 28 March – 4 April and 26 September – 31 October.
4. Avoid pinning human meetings to UTC. A UTC series moves for everyone who observes DST, twice a year. UTC suits automated jobs, not people.
5. Check scheduled jobs too. A job set to run at 09:00 America/New_York runs at 14:00 UTC in January and 13:00 UTC from 14 March, so anything in London that waits for it sees it an hour earlier for two weeks. The cron expression tool shows the next runs of a schedule.
6. Re-check when rules change. Governments sometimes change rules at short notice; Cuba gave eight days in October 2026. The dates here assume no further changes are announced before they occur.

To check a specific occurrence, enter its date and time in the time zone converter, which applies the rules for that date. The meeting planner compares working hours at today's offsets, so it does not show a future week. The world clock shows the current gaps, and the DST tracker each country's next change. City pages give the current offset for New York, London, Sydney, Brisbane, Auckland, Santiago, Mexico City and Vancouver.

For the general rules of running meetings across zones (overlap windows, rotation, invite hygiene), see the meeting across time zones playbook. The country-by-country rules are in the DST 2026 global overview.

FAQ

When is New York 4 hours behind London in 2027?

From 14 March to 28 March 2027 and from 31 October to 7 November 2027. The U.S. changes its clocks before Europe in spring and after Europe in autumn, so for those weeks only one side is on summer time.

Do Australia and New Zealand change clocks on the same day in 2027?

They fall back on the same day, Sunday 4 April 2027, but spring forward a week apart: New Zealand on 26 September and south-eastern Australia on 3 October. Sydney and Auckland are 3 hours apart instead of 2 for that week.

Does Mexico change its clocks in 2027?

Only the municipalities on the U.S. border, which follow the U.S. dates of 14 March and 7 November 2027. The rest of Mexico, including Mexico City on UTC−6, has not changed clocks since October 2022.

Sources

• IANA tz database, release 2026e (computed offsets and transitions); southamerica data file for Chile.
• Energy Policy Act of 2005 (U.S. DST dates).
• EU Directive 2000/84/EC and the UK Summer Time Order 2002.
• Australian Government: time zones and daylight saving.
• New Zealand Government: daylight saving.
• Mexico: Ley de los Husos Horarios en los Estados Unidos Mexicanos.