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Daylight saving time 2026–2027: every clock change that affects international meetings

By the TimeSlotSync team · Last reviewed 12 October 2026 · Time zone data: IANA tz database 2026c

When the clocks change in each major region, the weeks when the usual gaps between cities are wrong, and the countries that never change.

Daylight saving time (DST) is the single most common reason an international call starts with half the attendees missing. The problem is not that clocks change: it is that different countries change them on different dates, and some never change them at all. For a few weeks each spring and autumn, the gap between two cities you know well is an hour different from usual.

This page lists every clock change between now and the end of 2027 for the regions that matter most to international business. The dates are not copied from another website. They are computed from the IANA time zone database (version 2026c), the same data your phone, laptop and calendar use.

Every clock change, October 2026 to December 2027

Dates and times are local to the region. "Local clock" shows what a wall clock does at the moment of the change. When clocks go back, the hour before the change is repeated. When they go forward, an hour is skipped, and a meeting booked inside it does not exist.

Governments occasionally change these rules at short notice. Egypt, for example, brought daylight saving back in 2023 after seven years without it. If a meeting really matters, check the live clock on the day. Our world clock shows the next change for any city.

The two "mismatch windows" that cause most mistakes

Europe changes its clocks on the last Sunday of March and October. The United States and Canada change on the second Sunday of March and the first Sunday of November. Because the rules are different, there are two windows every year when the transatlantic gap shrinks by an hour:

• Autumn 2026: 25 October to 31 October. Europe has fallen back but North America has not. New York is 4 hours behind London instead of 5.
• Spring 2027: 14 March to 27 March. North America has sprung forward but Europe has not. Again, New York is 4 hours behind London instead of 5.

A recurring meeting fixed in one city's time zone keeps its local time there and moves by an hour for everyone else during these windows. If the meeting was booked by someone in New York at 10:00, London attendees will find it at 14:00 instead of 15:00 for that week.

Note the London–Sydney column. Because Australia is in the southern hemisphere, its clocks move in the opposite direction to Europe's. The gap between the two swings between 9 and 11 hours over a year, and a weekly call can drift by two full hours between June and January.

Countries and regions that do not change their clocks

Most of the world's population lives somewhere without daylight saving. None of the following change their clocks in the period above (checked against the same database):

• Asia: Japan, China, India, Singapore, South Korea, the United Arab Emirates, Saudi Arabia, and Iran (which stopped observing DST in 2022).
• Europe: Turkey (fixed at UTC+3 since 2016), Russia (no DST since 2014), Belarus, Iceland.
• Americas: Brazil (abolished in 2019), Mexico (abolished in most of the country in 2022), Paraguay (fixed at UTC−3 since 2024), Argentina, Colombia, Peru, and the US state of Arizona.
• Africa and Oceania: most of Africa, including South Africa, Nigeria and Kenya, plus Queensland, Western Australia and the Northern Territory in Australia.

This matters as much as the changes themselves. When London falls back on 25 October, its gap to Dubai, Mumbai and Singapore grows by an hour overnight. Nothing changed in those cities, but every recurring meeting with them moves for the London side.

How to protect your meetings

1. Anchor recurring meetings to the person most constrained. Calendar software keeps the meeting at the same local time in the organiser's time zone. Make the organiser the person with the least flexibility, usually the one at the edge of their working day.
2. Check the week before each mismatch window. For the dates above, put a reminder in your own calendar to review standing cross-Atlantic and cross-hemisphere meetings.
3. Never book inside the skipped hour. In the US, 02:00–02:59 on 14 March 2027 does not exist. In Central Europe it is 02:00–02:59 on 28 March 2027 (01:00–01:59 in the UK). Overnight batch jobs and automated reminders scheduled in those hours may run late or not at all.
4. Write the time in both zones in the invite text. "10:00 New York / 15:00 London" lets people spot a mismatch before the call rather than during it.

The TimeSlotSync meeting matcher warns you automatically when a clock change falls between today and the date you are planning, and tells you which participant it affects.

Related guides

• Working-hour overlap between major business cities
• UTC vs GMT: what is the difference?
• Time zone abbreviations that cause mix-ups