I have taken non swimmers snorkeling and wheelchair bound folks fishing. I'll get you on the trip you are going to feel the most comfortable with and have the most fun with. That incident with the Skipper and Gilligan happened a long time ago. The only weather concerns over here, short of a hurricane, is very strong Gail force tradewinds. If it is to windy the captain has the call to cancel the trip.
Passenger safety is always the captain and crews number one concern.
If the trip is canceled the activity will be happy to reschedule you or give you a refund. Rain is nothing but liquid sunshine. You'll have to call the psychic hotline for that one. Boat, plane, car, nothing will bother me. Put me on a carnival ride as basic as the ferris wheel and look out.