I thought I'd summarize how I handle heat while running.
1. Eat properly during the day before your run so you'll have the energy you need to complete the distance AND to handle the heat.
2. Be well hydrated during the day and night before your run by drinking more liquids.
3. Use the urine test before and after a run to test for dehydration. A slight yellow color is ok. Anything very dark indicates dehydration. The darker the color, the more the dehydration.
4. When possible run earlier in the morning or later at night when the temperature is lower.
5. If possible, choose a course that has some shade. Pause in or walk through the shady spots.
6. Run so your perceived effort for the run is about the same as it would be if you were running in a lower temperature. This means you'll run slower to reduce the stress on your body from the heat. Save your speed workouts for lower temperatures. Remember: Spring and Fall are for training. Summer and Winter are for surviving.
7. Take walking breaks if you normally don't take them, or walking breaks more often if you normally do take them, to give your body relief from the heat.