I took pictures for my cousin's wedding earlier this summer. They had an outdoor wedding, and of course, it rained. I know some people can have outdoor weddings with sunshine, but because I was involved, it rained.
So we just took pictures in my Aunty's bedroom. (it was the wedding location, and she had a big patio door and a large room. We also thought the rain would let up and we could go outside eventually)
It rained on my wedding too, and they say it's good luck. However, as the bride and I discussed, that's probably what they tell us when it rains on our wedding day to make us not feel bad.