When conditions are cool and dry or breezy your dog will be able to stay reasonable cool when exercising. If the weather conditions are hot and humid or still they will be unable to cool their bodies and could easily overheat.
If your dog’s tongue is shaped like a shovel, wide at the tip, he is at his limit of his ability to shed heat. Cool your dog by wetting his fur all the way to the skin before exercising in warm weather.
If the water doesn’t reach his skin, it won’t cool him. Wetting the surface of the fur won’t help your dog, the water must evaporate off his skin for the cooling effect of water to work. And be sure your dog has access to plenty of water to drink, he needs to replenish the fluids he loses while panting.