When we were at Sheraton Vistana Resort over a Thanksgiving week, we noticed that some of the pools were warmer than others. But we definitely enjoyed swimming in most of them and none we visited were too cool to enjoy midday. It's been a couple years so I cannot recall which were warmest. If you find the pool nearest your condo too cool, try a different one. If you stay at Sheraton Vistana Villages (the newer resort, just one main pool area, I think) in the winter and the pool is too cool, let them know it at the front desk. Perhaps they'll turn it up. I've found most timeshare resorts to be very responsive in this regard... the owners want the amenities to be pleasant.