For cats and dogs it can be difficult dealing with the heat, especially humidity. Both can only sweat through their paws and need cool air passing over their tongue (hence panting), shaded areas and cool water to help keep their temperature down.
Dogs are not always the best judge of when they are over heating so it is our responsibility to read their body language and manage their exercise through time of day, how strenuous, how long for and where.
Petmates dog walks are timed outside of the peak temperatures and in places where the dog can help regulate its own temperature e.g. shaded bush walks or cool water places – usually both.
Cats prefer to look after themselves more so providing pockets of water in a variety of different places, not just one, and access to protected, shaded areas will help. My cat, Maxi, loved a bowl of melting ice near his favourite sleeping spot in the garden.
Both though would prefer to be in an air conditioned area just as we do, so think about letting them in the house if you usually keep them outside.