Asymmetric daylight saving time in the EU

2 hours ago 1

2025-09-14

In the EU, daylight saving time starts on the last Sunday in March and ends on the last Sunday in October. Why?

To make it more clear, "March to October" is "one month too long", if you ask me: 7 months of DST, 5 months of standard time.

Spoiler: I have not yet been able to find a definitive answer.

Equinox is in March and September. Since DST appears to be about sunlight at a first glance (but as we all know, timezones are chaotic -- and yes, that is that video), it would make sense to base it on something from astronomics, such as equinox. So I would expect it to end in September, not in October.

The situation in Germany

Funny enough, Germany (both East and West, I think) did not observe DST from 1950 to 1979 at all. They only started doing that again in 1980, where it was almost reasonable:

DST in effect April 6, 1980, to September 28, 1980

And then, from 1981 to 1995:

DST in effect from last Sunday in March until last Sunday in September

Yay!

Starting in 1996, DST was extended from September to October, because Germany had to follow a EU directive. So, I'm going to try to trace that directive and try to find out why it uses October instead of September.

Tracing the laws

I think this is the current EU directive:

https://eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=CELEX:32000L0084

It just says that "March to October" is what the EU members like the most.

In general, we won't find any reasons or background info in law texts. They just state the law and that's it. I still hope that I can gather some clues here, like where to look: Should I dig through EU protocols or German ones? Maybe French ones? I hope that by tracing these laws I can narrow down the search space.

The directive from 1994, which effectively changed DST in Germany starting 1996, is this one:

https://eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=CELEX:31994L0021

Again, it just says:

Whereas the date considered most appropriate by the Member States for the end of the summer-time period is the end of October and not the end of September as in the past;

But it acknowledges that it used to be September, so if that was the "baseline", then there must have been some reason to extend it.

Wikipedia mentions the following link:

https://webspace.science.uu.nl/~gent0113/wettijd/wt_text4c.htm

It (or rather, the English translation) claims:

Until 1995, summer time ended on the last Sunday in September, but from the following year onwards, it was extended by one month to align with the United Kingdom's summer time schedule

So, was it because the UK?

I found something from 1972:

https://www.legislation.gov.uk/ukpga/1972/6

No new insight here and, as it turned out, it goes further back anyway. Looks like the UK started DST in 1916 (and have been observing some form of DST ever since, if Wikipedia is correct):

https://statutes.org.uk/site/the-statutes/twentieth-century/1916-6-7-george-5-c-14-summer-time-act/

The following link mentions that the UK introduced DST shortly after Germany did:

https://www.theanswerbank.co.uk/History/Question951578.html

And indeed, Germany introduced it on April 7, 1916, while that UK law is from May 17, 1916:

https://de.wikisource.org/wiki/Bekanntmachung_%C3%BCber_die_Vorverlegung_der_Stunden_in_der_Zeit_vom_1._Mai_bis_30._September_1916

The end of DST in the UK appears to have been October all this time (I think?), but the start was also weird in 1916. We have the following situation:

UK: End of May until beginning of October
Germany: End of April until beginning of October

And this was during World War I. It's probably reasonable to assume that, during that time, nobody really cared about astronomics or symmetry in DST or anything like that. This was pure chaos.

So the whole thing is very fuzzy now. Was the change from September to October in 1996 simply a concession to the UK? They used October right from the start and then just kept doing it that way? "We've always done it like that"?

Where to go from here?

As mentioned above, the answer probably won't be found in laws. I'd rather expect protocols of discussions or hearings to contain clues. I was not yet able to dig up documents like that. The EU hosts an archive, but it doesn't go back far enough. My only hopes would be that some later discussions pick up that topic again, so I'll keep digging a little more. Or maybe there's a different archive that I just haven't found yet.

I've also briefly checked the IANA tz database, because it contains some commentary on when changed what and why, but without much luck.

So far, I've only focused on Germany, the UK, and the EU in general. Maybe checking the DST history of other EU members can give any insight.

If you have any info on this topic (with sources), let me know. :-)

Read Entire Article