Here is a dictionary example:
Bis Sonntag bleibt das Wetter schön.
I am wondering whether the weather on Sunday will be fine or not? That is, whether the day of Sunday is included in or excluded from the time duration "bis Sonntag"?
German Language Stack Exchange is a bilingual question and answer site for speakers of all levels who want to share and increase their knowledge of the German language. It's 100% free, no registration required.
Sign up to join this communityHere is a dictionary example:
Bis Sonntag bleibt das Wetter schön.
I am wondering whether the weather on Sunday will be fine or not? That is, whether the day of Sunday is included in or excluded from the time duration "bis Sonntag"?
The sentence doesn't say, probably because people don't care as weather forecasts tend to be wrong anyhow ;)
Like in most languages, bis in German expresses a time extent to a certain point in time. Because "Sonntag" has an extent of its own, this cannot be precise.
If you want to be precise, add the precision using "einschließlich" or (in cases) "ausschließlich", or adjust your point in time more precisely like "Sonntag, 12 Uhr"
Das Wetter soll bis einschließlich Sonntag schön bleiben (Saying you explicitly want Sunday included)
Ich habe das Auto bis Montag, 12:00 Uhr gemietet
It is inclusive, until and including Sunday.
See, for instance, https://www.hofer.at/de/infos-und-services/hofer-a-z/o/oeffnungszeiten/
Öffnungszeiten Die Hauptöffnungszeiten der Hofer-Filialen sind
Montag bis Freitag, 07.40 bis 20.00 Uhr
Samstag, 07.40 bis 18.00 Uhr.
It is not very likely that the shop is open Monday until Thursday inclusive, then closed on Friday and open again on Saturday morning, but search for others to conform this.
This shows the general usage of "bis" with week days
I am a native speaker of German. I would expect the weather could change worse during Sunday. But the weather change may be early or late during Sunday.
Saying
Bis Sonntag bleibt das Wetter schön.
is usually meant and understood as including sunday, I agree with @Mawg.
But this cannot be generalized. If we say
Bis Ostern muss das fertig sein.
or
Bis Weihnachten räumst du dein Zimmer auf!
Easter and Christmas are excluded.
A [device repair] craftsman saying
Bis Freitag ist das gemacht!
is another sample for exclusion (meaning: You can pick up your device on friday).
(Result with helpful comment from @Nobody below)
This is actually unclear.
For some contexts like opening hours (in Mawag's answer) it clearly is inclusive.
For the weather forecast I would expext the weather to change at some time on Sunday..
But an example like:
Fritz bleibt bis Sonntag.
..clearly means he will stay until and leave on Sunday.
Otoh
Ich bleibe bis einschließlich Sonntag
implies the I will leave on Moday.
I'm german (you can see it on my grammer faults I tried to correct with google) and it's definitely including sunday. HOWEVER: As it's about weather you can say that friday and saturday it will be nice but on sunday there will be rain. On most other sentences what I said at first would be true, but on a weather forecast you can't be sure. I think it would be the same in the english version. Okay, so then I will drink some beer, eat some Würstchen with Sauerkraut and read "Mein Kampf" like every german does on sundays. HTH.