The water temp in the GOM can get down into the 60F range. Not that often, but once in awhile. The air temperature near Galveston, TX was above 80F yesterday, not a lot lower today. I've seen ice and snow out there, but it's really rare. The closer to the beach you get, the colder it will be during a cold snap, both air and water temps, and close to the beach the water temp can get pretty cold, but never near freezing. But I've been as cold out there as anywhere in the world, with rain blowing in a 40-knot wind. The damp, and not being clothed for really cold weather made it really uncomfortable.