Hey Chach,
Helllo from another NHite! We went the last of Feb, beginning of March this year. It was gorgeous and swimmable the first two days we were there, then a cold snap came through, and it was jeans and sweatshirts for two days, then the rest of the week was beautiful, highs around 80. We went swimming every day except the two above cold days. The pools are heated, so the water is nice. The only caveat - we went to Typhoon Lagoon the day after the cold snap ended - only available time, and my kids were dying to go. The water in the wave pool and slide areas wasn't too bad, just a little chilly, but the water in the lazy river felt like Hampton Beach in June! BRRR! We were all going to go around first thing, as my middle DD was dying to try it, but she got in a tube started heading out, and we tried to get in but no way!! She did the whole loop and met us at the slides when she was done! The CR Hotel pool water was fine, and the slide was fun.
Just pack a little of everything, shorts, pants, Tshirts and a heavy sweatshirt - you never know!