In which hours are the groceries opened during weekend in Vienna?
I will arrive there Saturday before noon, I'd like to know if I should take the food for 2 days with me, or can I expect to buy some supplies being there.
06:00 to 18:00 at most on Saturdays, not opened at all on Sundays. There are exceptions for stores in airports and train stations. Here's a list of branches with special opening hours for Billa, a large supermarket chain.