It's hard to dress right for school in the fall. Mornings are usually cold and foggy, but it gets warm. A week ago it was hot, good for local vintners, but too much for me.
Humans are warm-blooded.
We produce heat like a car engine, and we need active cooling from air and sweat. A hot tub feels great for a while, but only for a while. NASA apparently lost the Mars Climate Orbiter spacecraft due to another problem converting units. My problem is that I wear a jacket to work in the morning, and then forget to bring it home in the evening. Here in California, I have the added problem that I often go home from school in my swim suit after PE, and then I forget to bring it back to school in the morning.