I once toured in southern Germany, Czechoslovakia (it was one country then), Austria, and northern Italy (in that order) from late September to the 2nd week of November. I was very lucky and had great weather. However, it was early november when I cross the Dolomites, and I got across the mountains just a couple of days before the first snows of the season arrived. Campgrounds were closed virtually everywhere in October. It's easy enough to find weather averages online. But to be honest, if Poland and Germany have already had snow, I would forget about touring there for this year.