Snow

Snow is comparatively rare near sea level in England, but much more frequent over upland areas such as Exmoor. The average number of days each year when sleet or snow falls in England varies from about 10 or less in south-western coastal areas to over 50 in the Pennines. However, snow rarely lies on the ground at sea level before December or after March, and the average annual number of days with snow lying in England varies from five or less around the coasts to over 90 in parts of the Pennines. On Exmoor this varies from 23 days on the high moors to less than 6 at the coast at Minehead, Porlock and Combe Martin. Despite their height, the coastal hills in the west of Exmoor have little snow lying due to the warming effect of the sea. The high coastal ridge between Countisbury and Porlock, however, sees more snow lying due to the prevailing winds blowing over the moors rather than from the sea.

The number of days of snowfall and snow cover varies enormously from year to year. At many places in lowland England in the last fifty years it has ranged from none at all in a number of winters to in excess of 30 days during the winters of 1946/47 and 1962/63. Even places near the coast experienced prolonged snow cover during these two winters, particularly on Exmoor. In heavy snowfalls there can be quite extensive drifting of the snow in strong winds, especially over the higher ground.

The occurrence of snowfall is linked closely with temperature, with falls rarely occurring if the temperature is higher than 4 °C. For snow to lie for any length of time, the temperature normally has to be lower than this. In the South West, snowfall is normally confined to the months from November to April, though Exmoor may have brief falls in October and May. Snow rarely lies here outside of the period from December to March.

On average, the number of days with snow falling is less than 10 per winter in the coastal districts of Devon, although slightly higher in Somerset. About 8-15 days is typical of inland areas, increasing as one progresses inland and eastwards. In higher parts of Exmoor more than 25 days per year are normal. A rough average increase of about five days of snow falling per year per 100 metres increase in elevation has been found typical in the south-west, with the altitude of Exmoor varying from sea level to 519 metres..

Lying snow is not a frequent occurrence in the South West, and in lowland areas about a third of years do not record any snow lying. In coastal Devon less than three days per year is a typical average. This increases to 5-10 days per year inland, again increasing inland and eastwards. Altitude is significant and a rough guide is an increase of about five days per year with snow lying per 100 metres increase in elevation. The high parts of Exmoor have more than 20 days per year. This is not particularly high for upland Britain: parts of Scotland have about 60 days with snow lying on average.

Snow on Furzehill Ridge

Despite being the mildest region of the British Isles, the south-west peninsula has experienced some of the most severe blizzards to affect the country. This is because of a set of circumstances that affect the UK only rarely. If bitterly cold easterly winds from Europe meet a slow-moving Atlantic depression situated off south-west England then a prolonged snowstorm accompanied by high winds is possible. An example is 18/19 February 1978 when fine snow accompanied by 25 knot easterly winds at temperatures as low as -2 °C deposited around 50 cm of snow in inland Devon and over 90 cm on Exmoor.