Your pointers are used to intense work, right? Then I totally understand your concern!
With summer heat, the most important thing is managing your activity schedule. Absolutely avoid the hottest hours of the day - get out at dawn and dusk when temperatures are much milder. During the day keep them sheltered, preferably in a shaded and well-ventilated space, and make sure they always have access to fresh water. Don't let them drink all at once, but small amounts more frequently, otherwise they risk digestive problems. Provide pools or tubs where they can get in on their own to cool off - pointers love water and it helps them a lot.
To keep them in shape without stressing them with heat, reduce training intensity but stay consistent! Short sessions early in the morning are perfect, maybe in areas with pools or streams where they can get wet. Avoid maximum effort in August; focus on building endurance gradually during cooler times. Watch their behavior - if they're panting excessively, if they become lethargic or stop eating, those are signs they're suffering from the heat. In those cases cut back activity even more and consider seeing a vet. Come September when temperatures drop you'll be able to get back to more intense programs without any issues!