Windchill is the rate at which the warm air surrounding your body is taken away by a colder wind. The faster the wind, the faster the warm air is taken away, giving the impression that it is colder than it actually is. If you were in a hot climate where the ambient air was body temeperature you would feel no temperature difference in the wind.
iirc with humidity, higher humidity levels make cold temps feel colder and warm temps feel warmer. But there is no actual change in temperature, and at the temperatures being discussed here, there will be little evaporation anyway
Last edited by Pat.w; 6th January 2009 at 05:01 PM.