I am an Atlanta native and cycle about 10,000 per year when I am there. The heat and humidity were not much of a problem for me, but I was used to it and currently am working in Riyadh, Saudi Arabia (Now, that is hot!!!). The big thing is to keep yourself hidrated and you will be fine. There are a lot of group rides in the area.

Check out www.bikesbl.org for more information. The ride calendar is excellent.

Tommy