The pools are ALWAYS heated to the same 80ish degrees. Always. (so in summer when it's 95 the pool will feel cold)
The outside air is not. If you're in the water on a COLD day and your neck/head gets wet from a splash, you're going to feel cold when that part of you is out of the water. The rest of you will feel warm, though.
And yes, at some point after our first stay in December 2010 when pools were open as far as I could tell the whole time, they've started closing pool areas when it's in the lower 40s.