Granite does not absorb water and therefore is not weakened by it. The Happies/Sads are volcanic tuff, which I don't think absorbs much water either. So as soon as the skies clear you should be good to go.
Tuff does most definitely like to drink and is definitely weaker after moisture and all rock is weaker when moist. Tuff is just another type of granite.
Tuff is another type of Igneous Rock. It is different from granite another type of igneous and correctly stated will soak up some water and be a little weaker. Though it is also dries out very fast and you will be fine.