Way too cold for me but sometimes the "feels like" temp is hotter than the actual air temp.
The thing with water parks is that if you're just floating on the lazy river, you're not very wet and sun would feel good. Being cloudy would make it feel cooler. If kids are getting wet and then standing in line for another slide, sometimes you're waiting in a shady area and it's chilly.
Personally I wouldn't consider a water park visit from Nov-March and I'm from NJ. It's just too chilly to have fun. Still, free entry is free! If you go, maybe don't go as soon as it opens, wait until 12-1pm when it's usually warmer.