The Sunday September 11, 2016 Master of All Terrain Half Marathon in Orlando, FL is an off road half marathon in the Little Big Econ State Forest. While Florida is typically still pretty hot for half marathons in September, I'd gather this course may have some tree cover to provide some shade (you'd have to confirm with race organizer). Very little additional information is provided on the website about this race, so we'll have to leave it up to you to reach out to the race organizer. For a direct link, visit the Florida half marathons page and scroll to September.
Florida half marathons 2016