The Wind Chill Factor 

If you refer to our 'Heat Loss' information page you will be aware of the 6 ways we all lose heat when out on the hills.

One of these is called 'Convection' and this is where cold air passes over the skin, removing the warm air and making the skin colder as a result.

Obviously logic tells us the colder the ambient temperature and the quicker the air flow, the more 'chilled' we will feel. Add to this natures variation that temperature drops the higher we climb and all of a sudden this 'Wind Chill' can be a serious issue to effect your enjoyment if you are not prepared for it.

Can it be calculated? The answer is yes, however the maths is quite complicated. So we have done it all for you and arranged the data in an easy to follow guide below to make things easier for us all to remember.

When the BBC weather forecast states 'today the forecast is a temperature for your area will be 0C, but it will feel like -6C, the 'feels like' is referring to the wind chill factor. The calculation is based upon an average clothed person walking at 3mph/5kph and relates to the skin temperature of their exposed bare face.

The additional parameters which can effect the reality of the feeling, will be altitude, wind speed, humidity, metabolism, type of clothing and speed of movement. The basic principle of the calculation is based on exposed skin 5 foot off the ground at sea level. For every 300m (1000ft) height gained, air temperature will drop between 1C and 3C.

So looking at the chart below, walking at 3mph/5kph at sea level in ambient temperature of 0C with a Strong Breeze of 30mph it will 'feel like' -8C. However if you climb 600m (1000ft) in exactly the same conditions it will 'feel like' -16C.

Keep in mind that the risk of frostbite increases rapidly when wind chill values go below -27C. It has been reported from the Antarctic Survey Team that at -45C without wind you can cope quite easily. However at -30C with wind they have been known to require the use of a hair dryer to remove clothes which had frozen solid!