Irish clocks move forward an hour early on the last Sunday of March, at 1:00 a.m., and back again at 2:00 a.m. on the last Sunday of October: the very nights, and the very moment, of the change in the United Kingdom. In 2027 the dates are 28 March and 31 October. Ireland has one legal oddity that matters to nobody's wristwatch but is worth knowing: in Irish law the summer clock is the standard one, and it is the winter months that are the exception.

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Next clock change in Ireland

Local time in each place. Computed from the IANA time zone database.

All clock changes 2026–2028: Dublin

The Rule in Practice

From the last Sunday in March to the last Sunday in October Ireland is one hour ahead of Greenwich Mean Time; for the rest of the year it is on GMT. In March the clock skips from 0:59 to 2:00, and in October the hour from 1:00 to 2:00 is repeated. The dates are fixed by a European Union directive that applies to every member state, so Dublin changes at the same instant as Lisbon, Paris and Berlin, and, because Britain kept the same rule after leaving the EU, at the same instant as Belfast. That last point matters on an island with an open border: if the EU ever ended the changes and the UK did not, Northern Ireland and the Republic could be an hour apart for half the year.

Standard Time Is Summer Time

The Standard Time Act 1968 put Ireland one hour ahead of GMT all year, at the same time as the British experiment. When that experiment ended, the Standard Time (Amendment) Act 1971 did not repeal the 1968 Act; it added a winter period during which the clock would show GMT. So, legally, Irish Standard Time is the summer clock, and winter time is a temporary departure from it. This is why the time zone database gives Ireland a winter offset that is technically negative daylight saving, and why the abbreviation IST can mean Irish Standard Time in July. Nothing about daily life differs from Britain. It only means that lawyers and programmers describe the Irish year the other way round.

Dublin Mean Time: The Twenty-Five Minutes Ireland Lost

Until 1916 Ireland did not use Greenwich time at all. Clocks were set to Dublin Mean Time, measured at Dunsink Observatory, which ran 25 minutes and 21 seconds behind Greenwich. The Time (Ireland) Act 1916 abolished it: when Britain put its clocks back from its first summer time on 1 October 1916, Ireland put them back by only 35 minutes and has shared London's time ever since. The change came five months after the Easter Rising and was resented by some as one more thing decided in London. For family historians it means that a time on an Irish document from before October 1916 is not GMT and needs twenty-five minutes added to compare it with a British one.

Born in Ireland? Getting the Birth Time Right

An Irish birth time before 1 October 1916 is in Dublin Mean Time. After that it is GMT in winter and one hour ahead in summer, with the same wartime complications as Britain in some years: Ireland kept summer time through the winters of the early 1940s. From February 1968 to October 1971 it was one hour ahead all year. Each of these changes the Ascendant and the houses of a birth chart, and a 25-minute difference is enough to move the Ascendant six degrees. The time zone data behind our natal chart calculator reaches back to Dublin Mean Time, so a time can be typed in exactly as the parish or civil record gives it.

Frequently asked

When do the clocks go forward in Ireland in 2027?

In the early hours of Sunday 28 March 2027: 1:00 a.m. becomes 2:00 a.m. and Irish Standard Time is back.

When do the clocks go back in Ireland in 2027?

On Sunday 31 October 2027. At 2:00 a.m. the clock is set to 1:00 a.m. and the winter period on Greenwich Mean Time begins.

Is Ireland on the same time as Northern Ireland?

Yes, all year. Ireland follows the European Union's dates and the UK has kept the same rule, so both parts of the island change at the same moment.

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