I wouldn't take a chance...
Hello Gretchen,
From what I have read... It's not good for the fish to a certain degree.
It's probably not a good idea to let the water get hot or above 84 degrees at a quick rate. It could kill them. I think a quick jump in temperature could also cause stress.. I have heard of people raising the temperature to kill "ICH" but I don't know if they do this with the fish in the water or not...
You might want to set up a fan so it's blowing on the water to keep the water cool.. another thing is turn the water heater off and keep the light off to help keep it cooler. Your best bet is doing what you can to keep the water from being to warm and keep it at the same temperature.