Here’s why the clocks go back in winter - and the date they change this year

With the nights now slowly getting darker and the weather turning distinctly colder, it’s a sign that summer is long gone and winter is fast approaching.

Households across the UK change their clocks twice annually in accordance with the changing seasons, moving them an hour forward or backward depending on the time of year.

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At present, our clocks are currently operating on British Summer Time (or Daylight Saving Time) after being put forward on 29 March.

But why do we change the clocks twice every year and where does the tradition come from?

Why do we change the clocks?

The clocks are put back every year heading into winter to allow people to start and finish their working day an hour earlier. However, it means that people have an hour less daylight at the end of the day, which can be less practical in the winter as the evenings become darker.

Daylight Savings Time (DST) is also seen as an effective way of reducing energy consumption, with claims people will use less light and heat, although this logic has been disputed.

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Where does the tradition come from?

The idea of DST is believed to have first been proposed by British-born New Zealand entomologist and astronomer, George Hudson, in 1895.

Hudson’s shift work meant he could use his leisure time to collect insects and led him to value after-hours daylight.

In 1895, Hudson presented a paper to the Wellington Philosophical Society proposing a two-hour daylight-saving shift. This proposal gained considerable interest in Christchurch, leading him to follow the idea up in an 1898 paper.

British builder and outdoorsman William Willet has also been credited with the invention of DST, who campaigned tirelessly for the idea to be introduced.

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Willet proposed that the clocks should be advanced by 80 minutes in four incremental steps during April and reversed the same way during September. Doing so would mean the evenings would remain light for longer, increasing daylight recreation time and also saving £2.5 million in lighting costs.

After his campaign, British Summer Time was established by the Summer Time Act 1916, beginning on 21 May and ending on 1 October.

The German Empire and Austria-Hungary organised the first nationwide implementation of Daylight Saving Time on 30 April 1916 as a way to conserve coal during wartime.

Britain and most of its allies followed suit, while Russia waited until the following year and the US adopted DST in 1918.

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Most places abandoned it just after the war ended, apart from Canada, the UK, France, Ireland and the US.

It grew in popularity again during World War Two and was widely adopted in the US and Europe from the 1970s as a result of the energy crisis.

Which countries use Daylight Saving Time?

Most areas in Europe and North America, including Canada and Mexico, still observe DST, but it is generally not observed in countries close to the equator, where sunrise and sunset times don’t not vary enough to justify it.

Some countries only observe DST in some regions, with only parts of Australia, New Zealand, Fiji and Samoa, observing it, while Asia and Africa do not follow it at all.

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When do the clocks go back this year?

This year the clocks will go back an hour on 25 October, meaning people can enjoy an extra hour in bed as the clocks revert to Greenwich Mean Time (GMT) at 2am.

In early spring, on 28 March 2021, the clocks will be put back forward again.

In the UK, the clocks go forward an hour at 1am on the last Sunday in March, and then back an hour at 2am on the last Sunday in October.

When the clocks are an hour ahead, the time zone is referred to as British Summer Time (BST) and there is more daylight in the evening during this time, with darker mornings.

When the clocks go back, the UK is then on GMT and there is more daylight in the morning, with darker evenings.

A version of this article originally appeared on our sister site, The Scotsman.