We went to CC last year around mid-March. The weather was beautiful. Probably upper 70s/low 80s. I hate cold water and had a very hard time getting in the ocean. I wanted to snorkel so bad, so my DH encouraged me to get in. It was cold for a while. So cold it was a little hard to catch our breath. It took a good 15 minutes to get used to it during our snorkel and there was no way I would go back in after getting out. This year we are bringing shorty 3mm wet suits. I hope we can enjoy it more. We are from Houston, so we aren't used to the cold.
We went to CC in June one year and the water was a little cold getting in, but we got used to it pretty quickly. I had no problem in June getting in and out of the ocean.