You've posed an interesting question. I would say yes, unless they're on a surge protector. I would THINK that any damage to occur would be to the UTH only. Then again I guess it depends on how bad the storm is (and how warm your viv is). We've had a couple of thunder storms lately, but my UTH has been off when they've occured strictly because of the warm front that moved in with these storms. My viv was staying at 80 plus without using anything! The snake actually saught shelter under his water bowl...cooler there.
Your question makes me think of another related question:
What do you do to keep your corn warm if there's a power outtage (especially in the winter)??? My neighborhood seems prone to outtages in inclimate weather.