Daylight saving time

seasonal adjustment of clocks

Daylight saving time (DST) or summer time (ST) is a time to keep during summer. During the summer months, the sun stays visible for a longer time, and sunset happens late in the day. For this reason, certain countries advance the time by one hour near the start of summer, and put it back one hour during autumn.

A map showing countries that use daylight saving according to each hemisphere as of April 2023.
  DST in the northern hemisphere summer
  DST in the southern hemisphere summer
  DST no longer used
  DST never used
Diagram of a clock showing a transition from 02:00 to 03:00
Clocks are advanced by one hour during the very early morning at the beginning of DST.
Diagram of a clock showing a transition from 03:00 to 02:00
When DST ends, clocks are set back (as if to repeat one hour) during the very early morning. Specific times vary.

DST helps stores that sell to people after they get off work, and it doesn't hurt farmers and others whose hours are set by the sun. It cuts traffic accident rates. Sometimes it can reduce energy costs, but it can also increase them.

Most of the world's countries do not use DST, but it is common in Europe and North America.

The United States, Australia, the United Kingdom, Canada and many other countries have DST. These countries also have regions that do not have DST:

Iceland, Russia, Belarus, and some parts of Ukraine are countries in Europe without DST.

Europe change

Since 1971 all clocks in the European Union have changed on same dates and at the same time, 06:00 GMT.[1]

European Summer Time begins (clocks go forward) at 01:00 UTC on the last Sunday in March, and ends (clocks go back) at 01:00 UTC on the last Sunday in October:

Start End
28 March 2021 31 October 2021
27 March 2022 30 October 2022
26 March 2023 29 October 2023
31 March 2024 27 October 2024
30 March 2025 26 October 2025[note 1]
29 March 2026 ? 25 October 2026
28 March 2027 ? 31 October 2027
  1. If the 2018 Commission proposal had been approved by the Council of Ministers, and member states opted to remain on winter time year round, the October 2022 clock change would have been the final clock change.

United States change

The following table lists future starting and ending dates of daylight saving time in the United States:

Year Start End
2021 March 14 November 7
2022 March 13 November 6
2023 March 12 November 5
2024 March 10 November 3
2025 March 9 November 2
2026 March 8 November 1
2027 March 14 November 7

Permanent GMT+1 change

Permanent Summer Time has support in some northerly countries such as the UK. It was tried in the British Standard Time experiment, with Britain remaining on GMT+1 throughout the year. This took place between 27 October 1968 and 31 October 1971.

There are proposals for GMT+1 in the winter, and DST summer time (GMT+2) in the summer. In favour are most city dwellers: children do not have to come home after school in the dark, and late afternoon and early evening activities benefit. In favour also were those concerned with accidents, because both accidents and fuel consumption go down.RoSPA suggests this would reduce the number of accidents over this period as a result of the lighter evenings.[2][3][4]

Against are many farmers in northerly latitudes, because sunrise would occur in winter at about 10:00 in the morning. However, in March 2010 the National Farmers Union said that it was not against Single/Double Summer Time, and is in fact relatively neutral, with many farmers expressing a preference for the change.[5]

Automatic adjustment change

Most mobile phones and computers connected to the Internet will automatically adjust their clocks for DST. Some computers will not adjust or will adjust the time incorrectly or on the wrong date. Also, computers with more than one operating system may be incorrectly adjusted twice or more when each operating system boots.

References change

  1. British Summer Time Archived September 2, 2016, at the Wayback Machine
  2. "Press Release October 22, 2008 It's Time for a Change to Save Lives and Reduce Injuries". RoSPA Press Office. Archived from the original on Mar 17, 2009. Retrieved Sep 22, 2016.
  3. "British Summer Time (BST)". NMM – National Maritime Museum. Archived from the original on 2009-08-02. Retrieved 2016-09-22.
  4. Jha, Alok (Mar 29, 2010). "Lighter Later Guardian Article". The Guardian. London.
  5. "Should we change the clocks?". National Farmers Union. Mar 18, 2010. Archived from the original on Mar 30, 2010. Retrieved Sep 23, 2015.

Other websites change