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The big freeze will envelop the South tonight as the Arctic weather conditions send temperatures plunging as low as minus 10C (14F).

Scotland has borne the brunt of the cold weather so far, but Met Office forecasts suggest that England and Wales are about to suffer the worst temperatures, with a similar freeze on Wednesday night across Wales and southern England. Even during the day, temperatures are unlikely to stay above freezing in many places.

To add to the misery, a belt of sleet and snow showers running down through East Anglia and the South East could leave 1cm (0.4in) of snow on the ground this morning. It could also wash away the grit spread by councils during the night and leave widespread ice on roads and pavements during the morning rush hour.

This brief shower aside, conditions are set to remain dry in what is becoming a very dry winter. However, with such thick frost expected this week it could look like snow first thing in the morning. And because conditions are also calm, with hardly a whiff of a breeze, there will be plenty of dense freezing fog hanging around.

This can produce the strange sight of ice crystals falling out of the air and settling on the ground, which can look like snow has fallen.

Extreme cold such as this is often seen in the glens of the Highlands during winter, but is more unusual farther south. The coldest temperature in England last winter was minus 10C at Copley, Co Durham, in February, but the cold was not as widespread, nor as prolonged, as the present bout.

Mid-January is often the coldest time of the year, even though the daylight is growing longer, as an old saying goes: “As the days grow longer, the cold grows stronger.” This is because the seas around Britain take a long time to lose their heat stored up from last summer and, as they grow colder through January, they give less insulation from cold blasts of air sweeping down from the North or East.

The problem this winter is that the weather is stuck in a rut. For weeks, high pressure has sat over or very close to the UK, blowing a steady stream of cold air off continental Europe and trapping the cold down on the ground. Because this type of weather blocks out our usual wet but mild Atlantic weather it is called a “blocking pattern”, and is difficult to budge.

There are signs that by the end of this week the high pressure system may start to slip southwards and open the door for Atlantic depressions to roll back in, bringing a welcome blast of mild, but wet air. And the Met Office still stands by its long-range forecast of a milder end to the winter.

Even if this winter proves to be the coldest for many years, both here and in other regions of the world, it makes little difference to the overall trend in global climate. The weather can fluctuate wildly from year to year, but the big picture becomes clear only over decades and centuries.

Even in medieval times, when the climate in Europe was fairly benign, there were some astonishingly brutal winters. In 1205, for example, the Thames froze from mid-January until March. As one chronicler recorded: “No ground could be tilled, and frozen ale and wine were sold by weight.”

The big freeze is also taking its toll on the sporting programme. Four FA Cup third-round ties were cancelled on Saturday and there are doubts about whether this evening’s tie between Blyth Spartans and Blackburn Rovers can go ahead, with temperatures forecast to drop to minus 2C in the North East.

Yesterday’s race meeting at Plumpton was cancelled because of freezing temperatures and there will be no racing at Ludlow and Taunton today.

Today

A very cold start with frost and ice. Dry and sunny. Snow showers likely in the South East. Very cold again tonight

Tomorrow

Becoming cloudy with rain in Scotland. Rest of UK dry and sunny. A bitterly cold night in southern England and Wales

Wednesday

Cloudy with some rain, sleet or snow. Bitterly cold night in southern England and Wales

Thursday

Turning milder in the North, remaining cold and sunny in the South, cold at night

Friday

Thicker cloud, rain in the North, dry and cold in the South with some cloud, remaining cold at night