Can't decide whether to wear a t-shirt or a jumper lately? It's feeling particularly chilly all because of one key ingredient...

The dew point! While the air mass is decidedly chilly and unseasonably cold for the time of year as its streaming down from the north, it's also a very dry air mass.

That means that as well as low air temperatures, the dew point temperatures are also low.

So even despite the light winds, if there is no sunshine breaking through the clouds then a t-shirt will almost certainly not feel enough to keep you warm.