If your body is 98.6, why does it feel hot when it's 98.6 outside?

If our internal temperature is usually around 98.6°, why does a 98.6° day feel so hot?

Well, with all the processes it takes to stay alive, our bodies are like an engine, constantly running and producing heat-- even at rest. So to keep our core temperature constant, our bodies are also working, non-stop, behind the scenes to blow off heat to maintain that internal temperature.

You see, 98.6° is not an automatic default that comes about without effort; it takes constant work to maintain that temperature dynamically.

Two of the major ways our bodies cool off and maintain a normal temperature are by 1) sweating and 2) radiating heat.

The problem is, when the outside temperature becomes hot (and especially humid), those two methods become less effective.

1) Hot and humid conditions make sweating much less effective, as there's already too much moisture in the air. The sweat drips off the body, instead of evaporating to cool the skin.

2) And when the outside temperature is the same as the inside temperature, it also makes it a lot harder for heat to get radiated out of the body. Heat travels from hot places to cooler places-- which is why we like to open windows in hot rooms, for example. However, if it's just as hot outside as it is inside your hot room, opening a window is not effective.

So if the engine (your body) keeps humming along and creating heat, but the outside conditions won't allow the body to effectively disperse the excess heat that it's creating, then the plusses keep plussing, but the minuses can't minus-- and the body gets hotter, making 98.6° feel HOT!

(By the way, heat dumping helps the body radiate internal heat and cool off the core faster than it can on its own, regardless of outside temperature or humidity. To follow the analogy above, heat dumping always keeps a temperature outside of the room that will cool off the hot room if you open the window. Good heat dumping products keep a constantly cool temperature, no matter how much heat is getting dumped into them).