hi spirit,
in my experience, my UTH (exo terra heat wave 8x8) ran just over 100 degrees directly on the glass. i ended up having to get a thermostat to keep the temps down to about 89 on the glass and 86 on top of the substrate (aspen).
and from what i gathered from my research, there is another brand out there (zoo med i believe) that sells two types, one that runs 90f and the other 100f.
hope this helped!