Reply To: How cold will it be tomorrow?

As @matt describes, there’s no such thing as “cold”. However, our perception of cold is dependent on rate of heat loss (particularly to our skin surface). That heat loss is dependent on a number of things, but for the purposes of the question let’s assume we’re standing, our skin’s moisture and the air’s humidity remain constant, the wind is zero, and the sky is cloudy with a low cloud deck, like a northern winter’s day.

In that case, the rate of heat loss will be largely dependent on thermal radiation, which goes as the 4th power of the temperature difference. So for the rate of heat loss to double (twice as cold), the temperature difference required is not enormous. A quick calculation puts it at -44.5C, assuming we were using Celsius for the scale and body temperature for our reference. Seventy five below if everything is in Fahrenheit.