New tank, high humidity, low heat

Hey there I'm new to owning a corn and just set up an exo-terra 12 x 12 x 18 tank with cypress mulch substrate (about 2 inches of it), an under the tank heater and an exo-terra sun glow 15w lamp. After 6 or 7 hours keeping the thermometer on the substrate over the heater I'm getting around 80F with the lamp on. Humidity with the hygrometer directly on the substrate is around 90. I'm currently testing the 'cold' side temperature and humidity at the top of the tank to get a better idea of the air. I've been reading that temperature of the hot side should be 85-90F, any tips on how I can get the temp up? Is 2 inches of substrate too much for a small UTH? I have not gotten my snake yet so right now I'm just trying to test out the environment. Any help is appreciated!

You should measure the temperature on the glass under the substrate, not on the surface. Corns like to burrow, so you want to make sure it's not too hot on the glass where he will likely go. You also want to use a digital thermometer instead of a dial, since they can be inaccurate. As for the humidity, it *should* dry out. I'm not sure how cyress mulch is stored, but when I bought my mulch that I use in my cages it had been sitting outside in the winter and was a little damp and took a few days to dry out. The light will help dry it out for you I think. Good luck and welcome to the forum!!

Thanks Ali, I'm gonna pick up a digital thermometer with a probe. My bag of cypress mulch was foggy when I got it, so it was definitely holding a bit of water. I will measure the temp of the glass where the heater is, what would you say is too hot?

you can turn off your heater untill you get something to controll the temp

Anything over 88 is too hot, the absolute max for a corn snake is 90. Usually you want to keep it between 82-85. If you don't have a thermostat I would get one, since an UTH uncontrolled can (and will!) reach around 130 degrees.