We took Jack to Upstate New York with us when he was about 9 months old. My husbands folks had a place on Lake Champlain. We got there and walked down to the lake. As we stood on the boat ramp, Jack was entranced by the waves. Then, all of a sudden, SPLASH! Jack was swimming around. He immediately swam right back to me.
He has never gone in the water willingly again. And, as for rain, he will hold it all day, just so he doesn't have to get wet. He doesn't go in the house or anything. He just doesn't want to go outside.