I've also been worrying about this. When I saw the warm side of my terrarium was hitting 86-87, I turned it down to 84 from 85. Going by the answers here the higher temperatures I was getting aren't that big a deal, but I think it's something to keep in mind if you're living in an area where the outside temperature is going to get really high-the comfortable range for snakes is 80-85, if you're leaving the house and don't have climate control on, make sure your thermostat is set for the lower end of their comfortable spectrum to accomodate possible spikes in temperature.