I love summer. I love the heat. It takes a lot to make me hot. Unfortunately running and heat just don't mix well until you finally get acclimated. Also unfortunatly....I'm not acclimated yet! I seem to do better in the mornings when it's cooler, but the afternoon runs (which 3 out of 4 runs a week are) become so draining. I can't even use my apartment gym anymore because they started charging for access. Whoever heard of an apartment charging to use the equipment?! This economy is really changing things. Anyhoooo.....
I went through this a bit last year, and I'm sure I'll be going through it every year. What I've learned so far:
There's not much you can do to get used to the heat except just get outside. Be careful though...run during the cooler parts of the day like early morning, wear technical clothes, put on sunscreen, and (one of my favorites) wear a visor. Hats are cool too except you want something that will breathe. You don't want something trapping heat on your head. Visors give you the best of both worlds.
Hydrate!!!! I can't stress this one enough. After 25 minutes of intense cardio start drinking sports drinks. Drink enough water before the run too so you don't start running dehydrated.
If you are feeling woozy or dizzy or anything like that, stop running and start cooling down. Get in the shade, drink water, poor water on yourself, whatever it takes to cool off. Heat exhaustion and heat stroke are very real threats in the South, but it's possible to encounter them in cooler parts of the world too.
All in all, take advantage of the races during this time. Racing season is really kicking off, and they're great ways to meet new people and stay motivated.