Heat can be a problem for dogs. It's why during the hottest months here in Lake Mary, we often recommend waiting for morning or evening before giving dogs a long walk (short walks are okay and recommended). Furry/hairy dogs, especially, can be at risk for problems in high heat.
But avoiding extensive heat is only part of keeping your dog safe. The real problem, at least locally, is humidity.
It's not always the heating up that's the problem. It's the cooling down. Dogs cool down using their tongue by panting, which takes out moisture from their bodies and makes it easier for them to stay cool.
When there is a lot of humidity, the moisture on their tongues is unable to evaporate. They may have a hard time cooling down, and may become even hotter than they would have on an otherwise hot day.
All dogs need walks. Even on hot days it's a good idea to give your dog a walk, even midday, to get their legs stretched out and their muscles moving. But it is also important to pay attention to the weather, and not just the heat. High humidity means that long walks outdoors may be dangerous for dogs, especially if it is also a hot and sunny day. Your dog does need walks every day, but safety should still be a top priority.