The difference between the actual temperature and how freakin' cold it feels because of the wind is called wind chill. The wind carries away residual body heat from around you, which makes it feel colder than it is.

According to the National Weather Service wind chill is computed as:

T(wc) = 0.0817(3.71V**0.5 + 5.81 -0.25V)(T - 91.4) + 91.4

T(wc) is the wind chill, V is in the wind speed in statute miles per hour and T is the temperature in degrees Fahrenheit.

Celsius wind chill (using V as the wind speed in kilometers per hour and T in degrees Celsius) is:

T(wc) = 0.045(5.27V**0.5 + 10.45 - 0.28V) (T - 33) + 33

For example, if it's 32 Fahrenheit, and the wind is 40 MPH, it feels like 0 Fahrenheit. Brrrr.