In reply to hms:
I can't add much to that regarding walls, since I never go to walls in Ariège (we have a good training wall at Chez Arran), but I've just looked at the forecast for the weekend and it doesn't seem that bad to me. Certainly seems mixed, at worst.
Add to that the number of sheltered crags, and I certainly wouldn't be expecting to have to go indoors to find good climbing. My top recommendation would be Genat, for all grades 6a+ upwards but better in the 7s. Other alternatives include Les Toulousains, Grotte de Sabart and Petite Grotte (at Alliat) - this last one is right next to one of Ariège's premier grade 7 crags, Passe Muraille, so if it clears up, or if it looks threatening, you can easily switch sectors to get the best routes at any time.
It's extremely rare that no climbing is possible in Ariège if you're climbing grade 7s.