I did Switzerland in mid- to late-September and it was great. Before we went we took a German course from a native speaker who'd only been in the U.S. a couple years and, since it was German, we learned mostly about Germany. But I'd think September would be good for Germany.

http://www.visitireland.com/aboutireland/weather.asp

http://www.bbc.co.uk/weather/world/c...ml?tt=TT003650