I also ski on Smith Lake. The lake being river fed and being so deep it takes a long time for it to warm-up. However, the water temp is very nice during our Hot Summers. We usually go out a few times in May but Memorial Day seems to be about the time you can really get out on the lake and enjoy it. I am cold natured so I wear a Chill Skin under a shorty wet suit until it feels comofortable to me. My son and daughter wears a shorty wet suit, my wife won't get in the water until it is hot. There are some charts which tell you water temps and the reccomendation of wet suits.