I have been 3x the first week of January and each trip we were able to take advantage of the pools. I wouldn't say water park weather, but for sure pool weather! The people we talked with each time had said the weather had been nice enough for a while that many people had been swimming for the weeks before.
ETA: We even swam at night! It was definitely a bit chillier but still fun. When you're from the Northeast, that sort of weather in the winter feels like a 90 degree day!