Any unregulated heat source can easily reach over 100 degrees. Also, if you have your substrate too thick, your snake won't be able to reach the heat unless it burrows, which is now even more hazardous, due to your unregulated heat source.

I'd suggest unplugging it and picking up a light dimmer. Usually they can be found at home depot for fairly cheap.

You will need to get a thermostat though, as a dimmer is just a temporary fix. I'd suggest a herpstat 1.
http://www.spyderrobotics.com

Also, go to your Walmart and find a digital thermometer that has a probe. They have ones called accurites which will be able to show you your cool side and warm side temperatures as well as your humidity.