If you have an electric fan of any sort, you can rig together a poor-man's swamp cooler by putting a big container of ice & water in front of the fan, turn fan on...as the air passes over the cold water, it cools the air. Helps as well if you get your hair wet. And you can use wash cloths, towels, etc. as cooling towels, too. If need be, get them wet and put them in the fridge...then when chilly, put 1 around your neck. Sit in front of the fan.
Lather, rinse, repeat.
Drink lots and lots of water. And alternate sometimes with some sort of electrolyte product like Gatorade.
If you live in a multi-storied home, then spend all of your time on the bottom floor. Even sleep there if you have to.