Whirlybird,
I recently lived a year in Stuttgart and hopefully can offer some encouragemnt re the weather. It was before I started learning to fly mind, so my met appreciation was (even) less than now.
We'd occaisionally get some radiation fog first thing on spring mornings, but it would burn off quickly enough. The thing I would warn about is the golfball size hail stones that the summer CBs can throw down. Only happened twice in my time there but many cars parked out in the open were damaged - if it were me I'd arrange hangar space at any planned stop offs in advance. Mostly though, I remember clear skies and little wind...
Good luck and hope you enjoy it. It's one of my eventual aims to fly myself there.
bfato