I really wouldn't worry too much about it. Rafting can be cold and
very wet but most outfitters know how to keep thier customers
comfortable. They will suggest that you rent a wetsuit if they expect
it to be uncomfortable.

There are also many trips that involve warmer water- Indeed, this time
of year, most everything is pretty comfortable. I'll be kayaking at
7,000 feet this Saturday and I'll probably just wear a T-Shirt.

I would select a moderate or easy warm-water river to start out and
call the outfitter and ask questions. If you will tell us where you
are located, we can give you some suggestions.

Randy