Today I take a look at a process that is known as ‘radiative cooling’, of which will be exampled very well indeed in the coming nights. Radiative cooling relates to the methods by which temperatures fall away at night. Through the autumn and winter period, when nights are particularly long, and we get clear skies, then the land cools quickly. Any 'heat' is radiated away from the surface beneath the clear skies. This process can be made even more efficient when a cold air mass is in place, just like we have at the moment. Equally, and very importantly, the process can be even more pronounced when there is snow on the ground of which can make both maximum and minimum temperatures lower than would be the case without snow cover.

Over the next few nights, primarily where there has been settling snowfall, then the snow cover will aid in the process of the land cooling beneath the clear, winter skies. As a result, both Sunday and Monday night are, regionally at least, likely to be the coldest nights of the winter season so far. Once the unsettled conditions of today have cleared away, parts of Scotland, N England, perhaps Wales and the Midlands are likely to see a few nights where clear skies will dominate. When this is combined with both the cold air mass over the British Isles and the surface snow cover, temperatures will plummet!

At the moment minimum temperatures may well fall to near -4C to -8C across S Scotland, N England and down into Wales and the Midlands, perhaps especially so on Monday night. However, more locally and regionally, minimum temperatures may fall to near -10C, clearly this aided by the snow cover and of which will mean a severe and harsh frost will develop. A general guide of the minimum temperatures, into Tuesday morning, are exampled below, but this won’t pick out these more extreme minimum temperatures which are possible.