• Drink plenty of fluids. It's extremely important to stay hydrated. If you're thirsty then you are already dehydrated; drink before you feel a need to. Be sure to drink throughout the day (stick to non-caffeinated beverages, preferably water). Also, drink 15-20 minutes before beginning your workout and every 15 minutes throughout the exercise.
• Replace salts and minerals: Heavy sweating removes salt and minerals from the body. These are necessary for your body and must be replaced. If you must exercise, drink two to four glasses of cool, non-alcoholic fluids each hour. A sports beverage can replace the salt and minerals you lose in sweat. However, if you are on a low-salt diet, talk with your doctor before drinking a sports beverage or taking salt tablets.
• Eat regularly. The heat can decrease your appetite, but it's important to eat normally. Try to eat small meals 5-6 times per day. Include lots of fruits and vegetables. Aside from being nutritious, fruits also tend to help with hydration.
• Wear light, loose fitting clothes that can breath. Cotton is always a good choice. If your outdoor activity produces a lot of perspiration, consider clothing that is designed to wick the sweat away.
• Wear sunscreen. Even if you exercise early in the morning or late in the evening, if the sun can reach you then you can get burned. Not only is a sunburn bad on the skin and potentially dangerous but it also hinders your bodies ability to stay cool.
• Use common sense and don't attempt strenuous activities that your body is not accustom to. Stick to exercises that you are very familiar and comfortable with.
• Check the weather forecast. It's best not to participate in intense outdoor exercise sessions when the heat index registers in the dangerous zone.

*Facts from Centers for Disease Control - CDC Atlanta, GA