How does the wind affect the 'feels like' temperature? Shireen explains...

Temperatures have taken a noticeable drop as we head into October.
Temperatures have taken a noticeable drop as we head into October. Credit: Elizabeth Longbottom, St Peter Port

As we head into October tomorrow, I think it's fair to say that autumn is very much with us.

There has been a noticeable drop in daytime temperatures - but most significantly we have had some strong winds: a strong force 7 at times throughout the week, tide alerts for the west coast of Guernsey and yellow and orange wind warnings in force in the shipping channel.

When we get these strong winds, we often talk about what the temperature 'feels like' temperatures. 

'Feels like' temperatures are different to the actual air temperature shown on a weather forecast.

The Met Office measures the 'feels like' temperature by using the expected air temperature, relative humidity and the strength of the wind at 5 feet (human height) as well as an understanding of how heat is lost from the human body during cold and windy days.

This is significant on windy days due to the effect of wind on the evaporation speed of moisture from skin: the stronger the wind, the faster the cooling of the skin. 

Strong winds have come into force across the Channel Islands. Credit: Mark Charlton, St Ouen

An example of this is in autumn or winter when winds blowing from a northerly direction make the 'feels like' temperatures colder than the actual air temperature.

On a calm day, our bodies insulate us with a boundary layer which warms the air closest to the skin. If it is windy, the wind will take the boundary layer, ie. the heat away from the body and the skin temperature will drop making us feel colder.