1. Heed warnings. If there are "red flag" warnings for extreme heat or bad air quality due to heat, consider working out indoors.
2. Get acclimated to rising temps. It may take a week or two to get the body to acclimate (or accept) the warmer temperatures. Start slow and gradually increase your workout times and routines to acclimate to the heat.
3. Hydrate. Drink plenty of fluids before, during and after an outdoor workout to keep your body temperature normal. Don't wait until you are thirsty to drink water.
4. Dress appropriately. Lightweight, loose fitting exercise clothing is best in extreme conditions of heat. And, avoid dark colors when the sun is full on.
5. Know your fitness level. Don't start a new outdoor exercise routine in the extreme heat when you haven't worked out for a while.