There's a difference between being in air at 105 F which is warmer tha I'd like, but perfectly survivable (with enough salt and water to make up for the sweating) and hving a core temperaure of 105F which would be a seriously bad fever (we are talking "call an ambulance and get them to hospital" bad).
In my experience you can pick stuff up at 50 C and carry it about. At 60 C you can pick it up, but only for long enough to put it down again. Much hotter than that and, if you pick it up, you drop it.
Other people's tollerance will almost certainly differ. Also it's interesting to note that people can drink coffee from cups that are too hot to hold. The mouth has a lot of blood vessels that can carry away the heat quickly.