[cynwoody]

If one concedes too much at such mild temperatures, one isn’t going to be comfortable at -40, by which time one does need a decent coat and at least one extra layer.

At least, at -40 you don't have to worry about °F vs °C.

And by the time you get to -50°C, you are at that odd number cited in the article, -58°F.

[Hieronymus]

After -40, it is, at least in my books, really cold and time to stay indoors, however you want to measure. it. You make a good point about -58—I’d been wondering why that number was so significant.