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The southern half of Britain has been in the grip of a big freeze this week. On Tuesday night the frost hollow at Benson, Oxfordshire, recorded minus 11.8C (10.8F), the sea froze off the coast of Dorset and ponds in the fens froze thick enough to skate on them. Unusually, the highest temperatures on Tuesday and Wednesday were in the Hebrides.

The reason for this has been the high-pressure pattern over the UK. As air swirled clockwise around this system, it swept in bitterly cold air from Europe and gave us a shocking taste of a freezing continental winter.

But this week the high-pressure system has slipped southwards, leaving the southern half of the country in the cold, while farther north the door opened for our typical wet and windy Atlantic weather to rush in.

Depressions off the Atlantic also tend to carry milder air swept off the North Atlantic Drift, better known as the Gulf Stream. This is why Britain is several degrees warmer in winter than similar latitudes in Canada. Over recent years, we have got used to unusually mild winters dominated by these warm airflows, but this winter the Atlantic weather has been blocked out by the high-pressure system.

The good news for those tired of the cold snap is that temperatures are rising as the Atlantic takes control of our weather. But with the return of mild conditions will come plenty of rain, in what has been a remarkably dry winter so far.