When I was a teenager in very northern AZ (about 5 mi from the state border) I worked at Lake Powell Wahweap Marina.
Each Jan 1 we had an informal contest to see who could get in the first water ski trip of the year but we wore wetsuits so it wasn't as much of an ordeal as it might have been.

It was also of course AZ so it wasn't quite as cold as it might have been by national standards.
We were at about 3500 ft so it certainly wasn't warm either but it was enough to briefly amuse teen boys. Now it's just a lame memory/story.

I took January and February off from my pool. I guess that means I'll have to take the plunge tomorrow. I can tell the water is still cold, since the pool is right below my window and I can hear the screams when people first get in! The screams are getting fewer each day, so I think tomorrow might be my day.