huckster, it's a hard call. We go down to FL every October. I have had really hot weather (tanks, shorts, etc.) and have had cold snaps come through where I needed a sweatshirt, t-shirt under and pants. It just depends. October can be iffy weather just like Nov/Dec as far as getting a cold snap, but for the most part it is warm.
I suggest packing at least 1 sweatshirt with you and some pants and a windbreaker just to be on the safe side. It's better to be prepared than to have to look for cold weather clothes once you are in FL.
Sue Ellen