Well, I typed a long response and then it got deleted, so here is my short response.
December cruise ... great weather temps in the 80s in the Bahamas
March cruise ... woke up in Miami on day of departure and it was 49 degrees. High that day was in the mid 60s and very gusty winds. Bahamas was a little better with temps in the 70s. News station in Miami said it was the coldest air of the entire winter season ... in March! St. T and St. M delivered the hot humid weather I was looking for.
You never know, but go with a positive attitude and you will have a wonderful time!