If our core temperature is 98.6 degrees...?

Question

we can catch hypothermia in 80 degree water. But can we catch hypothermia in 80 degree weather?

Answer 1

It would be a very rare case (I don't know if it has ever happened).  The reason is that water, being much more dense than air, is thus a much better conductor of heat from your body.  Air is a relatively poor conductor of heat (this is the reason storm windows are double paned, with airspace in between, and why wearing multiple layers of clothing is better than one thick layer), thus your body is easily capable of maintaining core temperature in 80 degree air versus water.  

Answer 2

hypothetically, yes. likely, no.

it is very unlikely since we create our own body heat.

in water, we lose most of our body heat because it just goes into the water.

make it a good day