See the doctor. If you have special risks, including obesity, heart problems, medical restrictions on your fluid intake, a low-salt diet, or prescription drug usage, or if you are over 65, talk with your physician before you go out.
Get in shape and acclimate. Almost all of us can improve our ability to tolerate high temperatures by acclimating to the heat. But just sitting in a sauna won't do it. You have to actually exercise for an hour a day in the heat for five to 10 days in order to improve your tolerance.
Take cover. Wear a wide-brimmed hat and light-colored, loose, breathable clothing, and try to stay in the shade as much as possible. Also limit outdoor exercise on hot days to the morning and evening hours.
Stay hydrated. Drink nonalcoholic beverages, like water and sports drinks. Beer doesn't count because alcohol dehydrates your system and interferes with heat regulation. (Kirwin says that he frequently responds to calls involving fishermen who drink beer on a hot day and don't understand why they end up dehydrated.) Excessive water drinking, however, can sometimes cause the body to flush out too much sodium, leading to a potentially fatal condition called hyponatremia. Your best bet is to drink enough water to stay a little ahead of your thirst and supplement it with salty snacks.
Buddy up. Heat illness can cause confusion and loss of consciousness. Keep an eye on your buddy, and have him do the same for you.
Don't downplay symptoms. If you start feeling sick in the heat, stop exercising and head for the shade or airconditioning. Drink water, eat a salty snack, and take it easy. If you see someone collapse in the heat, summon paramedics.
Watch your best friend. Dogs are more vulnerable to heatstroke than humans, due to their coats and inability to sweat. In the fall of 2003, an estimated 100 hunting dogs died in South Dakota when pheasant season coincided with an autumn heat wave. "Most guys are very conscious of their dogs' health now," says David Smith, a dove-hunting outfitter and owner of Texas Wild. "Many of them won't bring a dog on a hot day. When they do, they bring a dish and plenty of water. If only they'd take as good care of themselves as they do of their dogs."