We went last Nov and we packed a TON! We were so unsure of the weather!! We packed shorts and pants, short sleeve, long sleeve, sweatshirts. Honestly, we wore a ton of what we brought. It ended up being much warmer than we had suspected so we didn't need the pants very often.
However, we went for Thanksgiving 4 years agao. Same beautiful weather for our trip until the last day. A cold front blew through and it was COLD!!!! My dd was an infant and we had to go buy her something warmer to wear and a blanket.
IMO, it's not the best swimming weather. But, I'm from Texas and we like it to be HOT HOT HOT when we swim!! It was pretty warm when we were there last Nov but it was a little cool for us to swim. However, there were tons of folks swimming so not too cold for other people.