Tank Queen to the rescue! (You're too cool, Starmom)

If it IS a tank you have him in, there are a few things you can do. First and foremost is to foil treat the screen top. I have a pic tutorial I can PM to ya.
After that, type of substrate can affect humidity levels.

What enclosure exactly are you using (i.e.size), what substrate, and how are you measuring humidity? Pictures would Really help.