I'd also love to see the guards or other NPC's get sick if they are standing in the rain for too long and then go take a hot bath. Wouldn't it be hilarious and cool to see the lonesome guard standing outside a door in the rain sneezing and sniffling. Or even your party members? it could affect moral.. don't think your in the best of moods when you have a cold.
There's just so much you can do with this =)
Good weather everyone is happy high moral, rain sleep and cold = bad moral
