It should be fine. Dec was great. They temporary close the parks if it's too cold. They closed the parks for 3 days while we were down because of temperature
We just went last week and while there were days the air temperature was too cold to go, the water temperature was still nice. January is the coldest month in Florida and typically by March, the weather is warming up. In April, you may still have a few cold days but if the air temperature is in the high 60s, low 70s and if the sun is out, you should be fine.
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