Luckily it didn't rain on our wedding day, but the advice from LIGrumpyGirl is great - I didn't ask "what if it rains" until the day before and my WP said "well, there is an overhang on the balcony you could all just squeeze in or I guess we'll just move you inside to where we do the cake cutting" niether of which was an option that worked for me! Thankfully the weather was gorgeous (a few days before Hurricane Wilma hit) so it wasn't an issue, but definitely get a back-up location planned with your WP before the day!