In reply to Rick Graham:
> You can do a similar exercise heading South and West from Cham.
Exactly.
There's no reason to make guesses about "rain shadows".
When the time comes to decide, just look at weather forecast _maps_
like
http://weather.unisys.com/gfs/gfs.php?inv=0&plot=pres®ion=eu&...
or
http://wxmaps.org/pix/euro.vv.html
and simply drive in the direction that does not show moisture.
It does not hurt to have 30 or 40 guidebooks in the boot of your car, like I do right now.
How far you drive depends on how badly you hate moist rock and bad visibility, and how many days you're going for.
While Finale Ligure (and note there is a new guidebook for interior crags getting opened) is perhaps the quickest seacoast drive from Cham, sometimes the French Mediterranean coast is dryer -- like Toulon / Aubagne / Marseille -- new guidebooks for that region also.
Of course hopefully no need to drive that far: There's plenty of good multi-pitch at lower altitude SW from Cham in the Aravis, and ridiculous amounts of single-pitch around Lac d'Annecy and Lac du Bourget. And if need to drive farther, there is Presles.
No need to guess about historical tendencies, just find the most recent forecast _maps_ on the web.
Ken