Ahaha. Needs an umbrella spell!
Sounds like the group is planning to migrate over to the tavern with a minimum time in the rain?
EDIT: In the future, you could probably grind down a single 7pp rank of variable to 1 or 2 pp with enough stacked casting drawbacks to make a "petty magic" power, useful only for doing things like Control Environment (Keep the rain off me), or Transmute (my torn muddle clothes into pristine new even more stylish clothes). Normally drawback stacking in games like this is wildly discouraged, but I'd allow it for a vain arcane user for a purpose so narrowly defined. Just a thought!