4 ms·

However there's no confusion about how cold -40 is!

• jacquesm 13y ago
  Just having an outdoor heater that needed daily refuelling (in itself a small miracle) was an excellent way to learn how to guess the temperature by the effects on eyelids, lips, ears and nose. -40: move (while you can), especially if there is some wind to go with it.
• WildUtah 13y ago
  In Canada, it might be -40 K.