Heat Matt too hot.

For my tank I use Repti-Therm under tank heater with the... I think it's called rheo stat? The adjusting plug in for the heat. Even when I have it on the lowest setting it is at 100. Through the substrate it is about 94. Is there anything I can do to lower it? I also have the exo tera Rainforest heat mat, but it didn't get hot enough so I switched it out.

Getting a thermostat is your best bet.

I think it wold be good to change your thermostat. I use the Jumpstart thermostat and it turns off the mat once it gets hotter than the temperature that you set.

For now you should unplug your heat mat so it won't hurt your snake. You could use a heat lamp to keep it warm for now.

Def get a thermostat. I would unplug the heat mat until you get one.

Like everybody said, unplug it and get a thermostat.

94 is already to hot. But snakes often move the substrate around and lay closer to the bottom of the enclosure or directly on top of that.
By the time they would get "uncomfortable" to move, the damage is done. This can turn into a severe and nasty burn along the belly. Sadly, it happens quite often..

Like Kira said, that "Jumpstart" is a very low priced and good option. You can get it on Amazon and even without prime shipping it should arrive pretty quickly.

It doesn't take long for this damage to happen. Getting to cold will make a Ball Python sick if it goes on long enough. Getting to hot will kill them. Quickly.

Good on your part to check the temperatures and realize there is a problem.