The occurrence of snowfall is linked closely to temperature, with snow rarely falling if it is higher than 4 °C. For snow to lie for any length of time, the temperature normally has to be less than this. The number of falls also increases with altitude and latitude.
The average number of days with snow falling each year ranges from under 20 in the south-east of the area to over 30 on higher ground. The average number of days with snow lying is less, varying from about 7 to 20. As a comparison, Balmoral in Grampian averages 60 days each winter with snow lying. It is unusual to get accumulations of more than 15 cm of snow and places on the Wolds tend to be the most prone.
The monthly averages of days with sleet/snow falling and lying at Waddington and Lowestoft are shown below (a day of lying snow is counted if the ground is more than 50 % covered at 0900). Days of sleet/snow falling for Lowestoft have been estimated from 1 km grids (to the nearest day), as this station is not manned 24 hours a day.
One of the worst winters was that of 1947 when snow fell somewhere in the UK every day between 22 January and 17 March. Frequent snowfalls and low temperatures (a minimum of -21 °C was recorded at Woburn in Bedfordshire) meant that when the thaw did occur, accompanied by rain and severe gales, the effects were significant. In East Anglia, where the major rivers flow north-eastwards, the south-westerly wind drove water before it and waves pounded the dykes which eventually gave way. Most of the Fenland area was flooded and the army were called in to assist.
More recently, heavy snow and freezing temperatures were experienced in January 1987 when bitter weather arrived from Russia and Scandinavia, resulting in snow depths over 30 cm in Lincolnshire (36 cm at Cranwell on 14th), blocked roads and ice along parts of the coast.
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