Joanie I grew them in San Antonio for a number of years and we have a member in the Georgia Dahlia Society that grew them in central Florida. They grow dahlias in Australia in 110 degree heat so it can be done.

The issues are, do you have the time and devotion to give them the extra care that will be required? Another issue is selection of dahlias that are heat tolerant. A list of these tubers is found on the DS of Georgia website but that page is currently down. It should be back up tomorrow or the next day.
The secret to growing dahlias in the heat is to take steps, constant watering, mulching, and attention, to make sure they live through the heat until the cool fall temperatures arrive in your area. Then you will be rewarded with beautiful blooms just like in the cooler regions of the country.

Here is a link that might be useful: Dahlia Society of Georgia