A google on Florida (or Arizona) bicycle clubs will give you a list of same and check of their websites will turn up other centuries. IIRC the Tallahassee area club has a fall century, but don't know when.
Not quite as warm, the Smoky Mountain Wheelmen out of Knoxville have a late Oct century. A good bit hillier terrain than Florida however and temps could be in the 40s, or not.