We've been snowbirds for the past 12 years or so, escaping the New England winters by heading to Florida and the Gulf Coast of Alabama and Mississippi. We have no problem with the temperatures in northern Florida - compared to home, it's quite balmy there. Our first year we did venture further south to the Everglades and Key West. Both were fun to see, but we found it too warm, too crowded and too expensive for our tastes.
You can get a feel for the north Florida area by reviewing our stories and pictures at our website:
Toad Hall. Click on the "Our Travels" menu option and then "Wintering in FL".
There are lots of great state and local parks in that area - just look under the "Campground Reviews" menu option for "Florida".
Have a great trip!