Mine get this way occasionally too, even in high humidity - especially during winter months. How often are you soaking them? What is your humidity running at?
One option is to put a scent free lotion on the really dry areas. You could even use small amounts of olive oil, just be sure you don't get it in their eyes (use a very small amount). I usually use Bag Balm, but conservative amounts any scent-free moisturizing cream would probably be okay.
While I do agree with JoesMum above, it really seems like mine gets pretty itchy during these particularly dry periods, so I brush on a little vitamin E oil during soaking time. I use a soft toothbrush and just brush it all over, seems to feel good to my sulcata, he pokes his head out and leans in to the soft scratchy brush, brushing off the loose stuff while moisturizing the rest.