Btw. how does it work in English? In German it's ambiguous which weekend one addresses when saying "next weekend". Is it the coming one this week or the one in the next week? Different people interpret it differently if it is not inherently obvious from the context, like when talking about dates. I also noticed that sometimes the same person even switches between meanings. I think I do, too. But I don't know why.
Maybe it depends on when one says it. I could be totally wrong here, but earlier in the week, like on Mondays and Tuesdays chances for "weekend in the same week" are higher than towards the weekend (Thursdays and Fridays), then it's more likely to refer to the weekend in the next week. And yes, the week of course starts on Monday. ;-)
Not sure if it changes with dialects. :-? I assume that doesn't play a big role and is the same for all German-speaking regions.
On the other hand, "this weekend" is very well defined as the upcoming weekend in this week. It's only the term "next weekend" that can be problematic.