1. Choose a COOL time of day. Know your local climate. Dawn is best, although it comes early in June and July. In some areas, a sea breeze begins cooling things down in mid-afternoon. But in many inland areas the temperatures rise until early evening, 5 p.m. to 6 p.m., and do not cool off until sunset. Your after-work walk schedule may put you into the hottest time of day.
2. Select a route that includes shade. Avoid direct sun and asphalt or concrete. Natural surface paths under the trees are the cooler places to walk. These are also favored by insects, so choose an insect repellent if they bug you too much, and check for ticks afterwards. You can use the Google Map Pedometer to find a walking route - and use the "Satellite View" or "Hybrid View" to see where the trees and shade may be.
3. Drink, drink, drink. Drink a big glass of water (12 to 20 ounces) 60 minutes BEFORE you start your walk. That starts you off well-hydrated but you have a chance to eliminate any extra before you start walking. Then drink a cup of water (6 to 8 ounces) every 20 to 30 minutes along your walk. You can tell if you end up dehydrated after your walk if your pulse rate remains high and your urine is dark yellow. The latest guideline for walkers and runners is "drink when thirsty," so be sure to carry water along so you can do so as soon as you are thirsty. Avoid drinks with a high sugar concentration, as that can cause nausea. Water is the best drink when walking for up to an hour. If you are walking and sweating for more than an hour, switch after the first hour to a sports drink that replaces electrolytes (body salt).
Drinking Guidelines for Walkers
4. Make your own shade. Wear a hat with a visor or a desert-cap with flaps to shade your neck. Wear sunscreen to prevent sunburn, skin cancer and wrinkles. Wear sunglasses that filter UVA and UVB to protect your eyes. Wear light colored clothing.
Hot Weather Walking Gear - Top Picks
5. Watch out for heat disease. If you become dizzy, nauseated, have dry skin or the chills, STOP and try to get a drink. If you do not feel better, get medical help immediately. If you are under care for a medical condition, especially heart or respiratory problems or have had heat stroke previously, consult with your health-care provider about walking in the heat.
Signs of Heat Sickness
6. Take it easy. If you can't avoid the heat, lower the intensity of your walking workout so your body generates less internal heat. Slow down, especially when going uphill. Save the higher intensity workouts for cooler times.
7. Respect the heat. Think twice about exercising when the ambient temperature is above 90 degrees Fahrenheit (32 degrees Celsius) and the relative humidity is above 60 percent, according to the American Council on Exercise.
Heat Stress Risks and Exercise Guidelines from Gary Westlund.