In reply to Tricadam:
This site is based in the area and the best I've found:
http://www.arpa.veneto.it/previsioni/en/html/meteo_dolomiti.php
www.dolomitimeteo.it/en/ is decent too.
Have fun!! The south tirol app has a decent wether section for areas to the east around Selva too
Take a look at the various web cams too: it's not unheard of for it to be clear on one side of a pass and pissing it down on the other. Helped us choose where we're off to of a morning before!
Have fun.