J.P.
I am about an hour or so north east from Tampa and the weather is still very nice that time of year, not as humid as summer but you can still swim (December gets chilly). Hurricane season ends in October so I wouldn't worry about that and last year it stayed hot and humid through December. I like Clearwater Beach (if you have a vehicle), it is nice and relaxing. You will mostly see wild dolphins and stingrays.
Tampa is a pretty big place so I am sure you will find plenty to keep you busy. Here is a website with some different options.
http://www.visittampabay.com/visitors/things-to-do/