I am wondering what will be open and closed in Germany on the Aug 15 holiday.
We wanted to visit wineries on that day. Would they be closed?
Where will you be? It is only a holiday in regions that are predominately Roman Catholic:
Bayern
Hessen
Saarland
15 August is not a holiday in Hessen. I think I would check with the winery to see if they are open that day. I am sure they all have websites. My guess is that they would be open on a holiday since people are off work and are looking for pleasant ways to spend the day.