But no amount of tweaking will make wind chill more comprehensible. The language of “equivalent temperatures” creates a fundamental misconception about what wind chill really means. It doesn’t tell you how cold your skin will get; that’s determined by air temperature alone. Wind chill just tells you the rate at which your skin will reach the air temperature. If it were 35 degrees outside with a wind chill of 25, you might think you’re in danger of getting frostbite. But your skin can freeze only if the air temperature is below freezing. At a real temperature of 35 degrees, you’ll never get frostbite no matter how long you stand outside. And despite a popular misconception, a below-32 wind chill can’t freeze our pipes or car radiators by itself, either.
Daniel Engber – Slate Magazine has more on why wind chill is a silly and misleading number.