My contract states that it is their responsibility to have a rain back up plan be it a tent, inside location or whatever. I'm not loosing money because they do not want to have their event due to rain. If my client is having a event that rain will affect and there is no way for them to have a back up plan then I recommend they purchase a rain insurance policy. This is also one reason why I require full payment 10 days prior to a event. 1) I don't like chasing them down for payment at the end of a event when I'm tired and ready to go home and 2) It's far enough out that they can't determine the weather and decide not to pay me because it's probably going to rain and they've decided to cancel.