My fish tank is over 80degrees!!?

I'm experiencing a heat wave and the room my fish tank is located in is unbearably hot. With the heater off all day, the tank has managed to still skyrocket. It is about 82 degrees and I don't know what to do. I just got new fish and I don't want any to die from temp fluctuations or from it simply being way too hot. I tried putting ice cubes in the tank but I think I'm just making the problem worse because the temp goes back up a little while after. Anybody have any suggestions? This is New England and it's almost October...why is it so hot!?