We went last President's week and 4 years ago. The parks will be crowded especially on weekends. Last year, it was cold all week long - we had our fleece jackets on most of the time and didn't use sunblock once. We still went in the pool and it was 40-50 degrees warmer than home. In 2000, it was chilly a few days and warmer the rest of the time. So, the weather is iffy that time of year. If you are travelling from the northeast, it is busy and expensive - make your plans early!