100 F is hardly a temperature that could kill you, unless you completely neglect hydration. But not drinking will kill you happily at lower temperatures.

Also, living in a climate where winter temperatures often hover around the freezing point, you develop a healthy interest in it.

As an example: If it's been a few days below 0 C, and then it warms to 3 C, the snow on the sidewalks will have compressed to ice whose top layer will now melt and create absolutely lethal walking conditions.

Or if it freezes after having sleet conditions (0-4 C maybe), you get this craggy ice that's not as slippery but is uneven and thus a hazard in its own way. Also very miserable for bicycles.

Anders Celsius was a Swede. He knew.