This thread is great! I was just thinking about this yesterday, Monday. My wife and I went in the pool on Saturday afternoon, air temp 88 water temp 78. Initially, the water felt cold and it took my wife, it seemed like, forever to get in. She immediately said it was too cold and she was getting out. I just mentioned it wasn't too bad, as my teeth were chattering. No not really. It didn't take long to get used to it. The air temp helped tremendously.
Today, on the other hand, the air temp is only 80 and the water has dropped to 75 degrees. Not sure I'll be going in until at minimum it gets back up to, at least, 78.