I was thinking of going in late January or sometime in February
How is the weather & are you able to go in the pools
Are they heated
Also how is the crowd level
It is predictably any of frigid, hot, or comfortable or anything in between.
I have gone when it felt like a summer day and when it felt like it could snow. (It has snowed a few flakes in Orlando before!)
Pools are heated, but it is subjective on whether you can swim. Depends on where you are from and air temps.
You will need to pack with a variety of considerations.
Recheck the forecast the day before departure.
I saw a trip report with pics of a family from far up north where it was so cold that they conceded to their wintry costs,
Gloves, hats and scarves.
Don't assume that just because
You are from up North that the 30s will feel more balmy.
In 2014 we traveled and it was blustery/rainy in the 50s. We has a crappy winter in Virginia and 50s were always welcome as feeling Springlike. It was sooo cold to me in Florida. (I have since moved back and thought all the "cold" snaps did not feel cold at all this past winter.). And, the weather bounced between warm enough to swim and cold.
So, be prepared. We are unable to predict what kind of weather you will experience.