BAST, we were there this past December and January and swam every day, cold or warm. I should note that some of the pools were warmer than others. We stayed at the following resorts: Caribbean Beach, Animal Kingdom Lodge, Old Key West, Contemporary, and BoardWalk. Since we are DVC members, we also swam in the GF pools (both of them) one day while our daughter did the Pirates Cruise & Wonderland Tea Party. Midnight swims are a must on any of my vacations, so a lot of my swimming was in the middle of the night when it was the coldest outside. The "bulls-eye" pool at the Contemp was one of the warmest pools that I swam in, as was the BoardWalk's "clown" pool. I have found that the pool heaters run on timers and put out warm water at various times of the day and night. Sometimes you'll get lucky and be in the pool when the heated water comes out the water jets. Then you'll find yourself hanging out over those water jets just because it is warmer there. (As you can see, I did a lot of swimming during my past vacation.)