More like he won't be able to digest properly if the temps are too low. Then you risk a regurge. If it was me, and the UTH was getting here in a few days, I would just wait till I could offer my snake a true warm area for digestion.
Nanci
(Like yesterday afternoon it was a beautiful 75F out, but I didn't feed my box turtles because I know it's going down to near 30F tonight.)