Yeah, I have friends in upstate who predict 100 degrees. The good news that in Texas where it can get over 100 for months at a time, the dogs do just fine, as long as they have water and can get in the shade. Foolishly, I've been walking my dog everyday for the passed 10+ years, with no ill-effects to either of us. However...
I walk my dog everyday, so he gets conditioned to the heat. When we get short heat spells in Feb. - March, both of us are miserable during the walk.... no conditioning...
1. Have cool water available all the time. You might include ice cubes.
2. Keep an oscillating fan going continuously. Circulating air, even hot air is important.
3. Open two windows for cross-ventilation ... and get a window fan, if possible.
4. You might get some thing (muslin or burlap) cloth, wet it, and put it in the way of the fan, but not totally blocking. In comparatively dry climates, this works like a swamp cooler.
5. My Vet suggested that I soak my shirt and my dog when we walk in mid-summer... It works, but then we go into air conditioning.
A hot water bottle, filled with ice water... as long as you can trust the dog not to chew on it.
An inexpensive beach chair, as a place for the dog to sleep, to allow air to flow underneath.
Non carpeted flooring, mopped to make lightly damp, with a fan blowing over.
I think you can get a cheap A/C window unit for a few hundred bucks...
OR... come down to Texas where we have A/C, and cool off !