It has always been my understanding that hedgehogs are much more tolerant of higher temperatures, so risks of being too hot are considerably lower and not immediately threatening. Splatting can indicate overheating. Their natural environment is African deserts. Though our hedgies are generations removed from living in the desert, instincts tend to persist for many, many generations (at a minimum).
My breeder said that 85 - 90 degrees was a reasonable top temperature. I keep Sophie's max temp in the low 80s in the summer and aim for high 70s most of the time. I don't worry too all much if temperatures hit upper 80s, but don't typically leave them there very long. I'm pretty conservative and haven't tested the high temps.
I do, however, think that she (and all animals that tolerate it) benefits from a wider temperature range as being better than a year-round narrow range of just a couple of degrees. So, I like to see variances from about 73 to 87 degrees, with the high temps being of shortish duration.
I'm especially conservative about low temperatures, having heard too many accounts of hibernation attempts. Lowest recorded cage temperature so far this winter is 74.1
So far, even when I have let the temperature push into the upper 80s, Sophie has never shown the slightest sign that she cares. She has several choices of places to sleep, but always chooses the fleece burrow in her PVC tunnel.
