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Preliminary Dates for DST Switches

The Daylight Saving Time (DST) schedules in some countries may change on short notice.

Illustration of clock with arrow moving forward 1 hour.

Clocks are set 1 hour forward for DST in spring.


In most countries, DST schedules are stable, so the dates and times of future DST switches are unlikely to change. However, in some cases, the schedule may be altered in the near future. In these cases, the dates are marked as preliminary on timeanddate.com.

When Is a DST Date Preliminary?

Our researchers monitor political processes, public debates, and the time zone history in countries worldwide. Future DST switches can be deemed preliminary if:

  • there are clear signals in the political and public debate that the laws governing DST clock changes may be changed soon;
  • there have been recent changes to these laws;
  • there are unconfirmed reports about upcoming changes, but it is difficult to obtain reliable information from official sources;
  • the country has a recent history of several changes in the DST legislation;
  • the government announces DST switch dates and times at very short notice;
  • the information flow between government and population about a recent change in legislation is inadequate, and most people still follow the old rules;
  • there is political turmoil that can alter the DST or time zone legislation;
  • the country suspends DST during the Muslim month of Ramadan.

Please note: Non-preliminary DST switches can also change at short notice.

Antarctic Research Stations

Since Antarctica is largely uninhabited, the continent is not officially divided up into time zones. However, there are a number of research stations, each of which observes its own local time. Some stations use the time zone of the country that operates or supplies them; others observe the local time of countries nearby.

For some of the stations, the exact time and date of the DST change is sometimes not easy to predict as it depends on when supplies and personnel arrive for the summer season.

Stay up to Date

Check our Time Zone News to receive up-to-date information about DST and time zone switches.

If you have information about a DST switch that is listed as a preliminary date, please let us know.

Topics: Daylight Saving Time