Where are you from?? We are from Florida and lows in the 60s is chilly to us, especially if you're going to be on the water! Now, if you live in Maine and you swim in the lake water in Maine in May, then your view of things would be different! If it were ME, I'd definitely take a jacket and/or a sweatshirt for the evening and the water might be too cold for me. (BUT, I don't get in my pool at home unless the water is at least 80... )