Although daylight saving time has already begun this year in countries such as the United States and Canada, all of the European Union, including Germany, will change their clocks this coming Sunday. Of course, there are many countries in which this practice is not observed at all, and two years ago, the EU did actually vote to do away with it. This was expected to start this year, but there is still no consensus regarding whether to adhere to standard time or daylight saving time permanently.
For now, Germans will continue to turn their clocks back an hour, or "fall back," in the fall, and skip forward an hour, or "spring forward," in the spring, always wondering if it could be the last time. This is referred to as die Zeitumstellung, which makes sense as Zeit means "time" and die Umstellung can be translated as "the adjustment" or "the re-setting." The related verb is umstellen and the participle is umgestellt.
In German, the word die Sommerzeit is used to refer to daylight saving time:
Ist vielleicht wegen der Sommerzeit.
Maybe it's because of daylight saving time.
Ist das eine Stunde vor oder eine Stunde zurück?
Is it one hour ahead or one hour back?
Caption 29, Die Pfefferkörner - CybermobbingPlay Caption
Ich glaube, die Sommerzeit ist eine Stunde vor.
I think daylight saving time is one hour ahead.
Caption 33, Die Pfefferkörner - CybermobbingPlay Caption
You might right away wonder about the meaning of the word die Sommerzeit. Like in English, it does also simply mean "summertime."
Sommerzeit ist in Deutschland gleichzeitig Grillzeit.
Summertime is simultaneously barbecue time in Germany.
Caption 1, Grillzeit - Grill anzünden und los geht'sPlay Caption
Du grünst nicht nur zur Sommerzeit...
You not only flourish in the summertime...
Caption 5, Frohe Weihnachten - der ChristbaumPlay Caption
As you might guess, standard time is referred to as die Winterzeit in German. So, in order to be more specific about the time change, you can talk about either die Zeitumstellung von Winterzeit auf Sommerzeit (which will happen on Sunday) or die Zeitumstellung von Sommerzeit auf Winterzeit.
In addition to checking out the conversation in the Pfefferkörner episode above on Yabla German, see if you can follow this basic description of die Zeitumstellung in Germany. If you're an advanced learner, have a look at this overview.