J&V,
We did the Western Caribbean aboard the Grand Princess last November, saw Grand Cayman, Costa Mata, and Cozumel. Warm but not too hot. Wandered in town, in and out of the parks and stores, just in shirtsleeves. Sun's very bright, though, bring your sunglasses. Enjoy.
I have spent several Thanksgivings in Cancun and the weather has always been great. Warm enough for swimming, etc. but not blistering. And I cannot remember ever having rain.
We were there Nov. 2003 and the weather was perfect. It was around 85 and sun shiny. Definetly warm enough to swim in the ocean, but not the typical Hot as Heck Mexican weather. We actually had cold weather the sea day before arriving and even colder weather on the sea day back to Galveston. Each of our port stops were pleasantly warm though.
Generally you will find weather in this part of Mexico at that time of year a little unpredictable. It can be excellent - warm and sunny BUT it is the end of the rainy season - so it may also rain.
We are going on the Inspiration for the four night cruise out of Tampa to Cozumel on Nov 18 and were wondering the same thing if someone tells you can you please let me know at my aol address? It would much appreciated! Ro angelicro@aol.com