I live in Texas, and during the summer I ride in 90-100F weather.
It really is something you have to get use to. The more you do it, the better it gets. Last week, I nearly died trying to ride on a really hot day... but over the weekend I was fine. I just had to get adjusted.
It is really important that you DRINK LOTS OF WATER/SPORTS DRINK! One bottle will NOT cut it in that kind of heat. If I do a challenging 30 mile ride, I can drink through 1.5 liters in my Camelbac and 24oz in my water bottle.
I also find it good to have COOL water. Hot water is just... YUCK. How do I keep my water cool? I have a Polar water bottle. If you put ice in there, or freeze it overnight, you will have cool water for about 1-2 hours. If you have a Camelbac and put ice/water in there... it will stay cool for a good 2-3 hours.
Finally, LISTEN TO YOUR BODY. Learn what heat stroke/exhaustion is. And when you feel it happening, stop riding and take care of yourself.
Best of luck! Trust me, it gets better the more you do it!
"Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather, to skid in broadside thoroughly used-up, totally worn out, and loudly proclaiming: WOW WHAT A RIDE!!!!"