Readers reply: why do we wait until late March to put the clocks forward?

·7-min read

In the UK, the clocks go back by one hour in late October, seven to eight weeks before the winter solstice. However, they don’t go forward seven or eight weeks after the winter solstice in mid February. Instead we wait another six weeks, until late March. The amount of daylight by mid February (about 10 hours) is similar to that of late October. Why do we wait so much longer?
Mark Stephenson

Send new questions to nq@theguardian.com.

Readers reply

Why we change the clocks at all is the question. Stobbold

Changing the hour has always seemed a poor way of addressing the issues. In the summer, we have light far earlier, and far later, than we really know what to do with. For several weeks In the winter, it is dark at both ends of the day. It seems there is only a limited period, spring and autumn, when the precise time of dawn and dusk really matters. And the importance of that time, and where it falls within our daily lives, varies depending on the patterns of our lives, including precisely where we live. That is, it is an individual assessment. I feel it can take the best part of a fortnight to fully adjust from the hour change. Which is a bigger impact on me than would be not changing the hour at all. polygonum

In a way, the wrong question is being asked here. Daylight Saving Time (DST) is ineffective if the length of day is less than 12 hours, so there is a school of thought that says that clocks should be put back at the end of September after the autumn equinox. Interestingly, when the Netherlands introduced DST in the 1970s they chose the last weekend in September for putting clocks back, and it was only when much of Europe agreed to synchronise the clock changes that it was decided to delay the autumn change to conform with British practice. One consequence of the delayed autumn change is to abruptly switch many commuters driving home from driving in the light to doing so in the dark – a September change would give them time to gradually adapt. Rod Davis, Bristol

DST seems to have been brought into being largely to save fuel for heating, initially by Germany during the first world war, and soon copied by other countries in temperate, day-length-changing latitudes. Perhaps one reason for the asymmetry is that because the ocean retains heat, there is less need for heating in the earlier part of winter, but during the first few months of the year it stays colder, until the ocean has had enough solar input to warm up the land. The asymmetry might also be connected to agriculture and the timing of planting seasons, which again would be largely dependent on spring warmth. greendreamer

The asymmetry that Mark Stephenson notes has been built into the system almost from the beginning. Peacetime shifts have been in October since 1920, even when the shift forward was as late as mid-April. I suspect it’s mostly about giving farmers an extra hour of daylight to bring in the autumn harvest. Though the fact that October weather tends to be better than March weather for evening activities probably doesn’t hurt.

Changing to year-round summer time is attractive in theory but unpleasant in practice. With the current system, almost everyone in the country who works 9-5 will arrive at work in daylight every day of the year. On year-round summer time, even Londoners – who get some of the earliest winter sunrises in the country – would arrive at work in darkness for a few weeks every winter. People don’t like getting up in darkness, and this was the main reason why the experiment with year-round summer time in 1968-71 was dropped. Pete Appleyard

It’s very clearly based on when it snows in New England in the US. I live there, and not long after we turn the clocks back and deprive ourselves of that precious hour of light, the snow comes to make sure that we are huddled inside. Right in the middle of March we spring forward in desperate hopes that it will make the snow finally go away, although often it responds with a tantrum blizzard. The timing is close to exact, at least before global warming. I don’t know how the snow managed to reach this arrangement or why it’s observed in other places, though. Thomas1178

I should imagine it’s to do with what time it gets light in the morning, rather than overall amount of day light. If people are used to getting up in daylight in February (which most people working an “average” 9-5 job will be) then plunging them into darkness again, if only for a few weeks, might feel unpleasant. lexicon_mistress

I wondered this for a long time and couldn’t find a satisfactory answer until I came across an explanation based on the fact that the daylight “expands” asymmetrically post winter solstice. Apparently it gets lighter in the evenings more quickly than in the mornings until a certain point in the year, and the move forward to BST earlier would make mornings disproportionately darker. All something to do with the timing of the sun’s zenith and how it relates to our clock-measured midday. Bobposter

We used to put our clocks forward in early March. In the 1970s, following the oil shock, other European countries also adopted summer time. But they mostly went forward in late March, close to the equinox. Thus through the 70s we had a week or two on the same time as the Netherlands, Belgium and Federal Germany before they pulled ahead in late March. Eventually we harmonised clock change dates to the current system.

As to late March rather than early? The best reason must be that the seasons lag behind the sun. It’s not uncommon for early March to have heavy frost and snow in the mornings especially in continental Europe. October generally rarely suffers in the same way. Duncan Stewart, Denbighshire

I’ve never understood why we bother to change the clocks, given that we can’t actually change the amount of daylight we get, whatever people like to say about getting an “extra hour” of daylight when the clocks go forward. Surely it would be better to adapt one’s day to the best fit with the available hours of day/night. Changing the clocks twice a year is a pain in the neck. Robskydiver

Could be worse. For example, I was on a road trip a few years ago and Arizona doesn’t observe DST, but the Navajo nation does, so traveling from Utah through Arizona to the Navajo nation involved changing my clocks twice. In a few hours. For even more fun, Beijing insists that all parts of China are on Beijing time, so the sun rose in Tibet when I was there around noon. And if you think, fine, so you just open stuff around noon, no, Beijing doesn’t really go for that either. (I don’t know if that’s changed since they cut off tourism, though.) Thomas1178

It’s fairly straightforward, if a bit dumb. Let’s use a northerly city like Glasgow as an example (exact times will vary depending on location). Remember, the “target” dawn time is always after the change, so you have to wait till late March for dawn to be before 6am, to hit a target of dawn at 7am, post change. Similarly you wait no longer than October for dawn to be at 8am to hit the same target of dawn at 7am, post change.

Now, if you wanted a “symmetrical” (or, indeed, logical) clock adjustment window, relative to the equinoxes, if your target dawn time (post change) was 7am going in, your target should be 6am coming out (because clock numbers are just arbitrary markers, and daylight hours are now contracting). But because the change window system is based around trying to officiously make dawn hit the same arbitrary number (post change) coming in and out, like it’s a train timetable or something, the whole window is now skewed later in the calendar year by about a month.

I’m presuming this arose because proposing a common (post change) target time for dawn at either end of the year was simply an easier concept to “sell”. But it just makes an already very stupid idea even stupider.

The fact that the UK opted to stay in DST, in the face of flexible working and now mass working/schooling from home and staggered working/school hours for the foreseeable future anyway is the very apex of “don’t move my cheese”, tradition over practicality, “it’s broke, but let’s not fix it”, “don’t scare the horses”, nimby – *cough* – “modern” (rotflmao) British conservatism. HaveYouFedTheFish