The strongest winds are associated with the passage of depressions close to or across the UK. The frequency and depth of these areas of low pressure is greatest in the winter half of the year, especially from December to February, and this is when mean speeds and gusts (short duration peak values) are strongest. The graph shows a typical variation of the monthly mean speeds and highest gusts. The period November to March has the highest mean speeds and the peak gusts follow a similar pattern. Leeming is an open, but low and relatively sheltered, site in the Vale of York. Upland areas and coastal areas, particularly those exposed to the north, will experience stronger winds.
The variation in monthly mean speeds (average of a continuous record) and highest gusts ('instantaneous' speed averaged over about 3 seconds) at Leeming is shown below.
Another measure of wind exposure is the number of days when gale force is reached. If the wind reaches a mean speed of 34 knots or more over any ten consecutive minutes, then that day is classed as having a gale. Over the highest Pennines there are about 15 gales per year while along the coast gales occur on 5-10 days and low-lying places inland experience less than 5 gales per year. Wind speed is sensitive to altitude and local topographic effects.
There have been several noteworthy gales affecting NE England, accompanied by property damage and disruption to travel and power supplies. Examples include 16 February 1962 when nearly 2/3 of all houses in Sheffield suffered some form of damage as a result of winds accelerating as they crossed the Pennines. On 2 January 1976 a depression moving eastwards across Scotland to the North Sea brought storm force winds with an hourly mean speed of 70 knots at South Gare (Cleveland). More recently, the storm of 28-29 January 2002 led to rail and road transport disruption (with lorries overturning), power cuts (20,000 homes affected in the Tyne valley) and building damage.
The direction of the wind is defined as the direction from which the wind is blowing. As Atlantic depressions pass the UK the wind typically starts to blow from the south or south west, but later comes from the west or north-west as the depression moves away. The range of directions between south and north-west accounts for the majority of occasions and the strongest winds nearly always blow from this range of directions. Spring time tends to have a maximum frequency of winds from the north east, due to a build of high pressure over Scandinavia at this time of year.
The annual wind rose for Boulmer is typical of open, level locations across the region, with a prevailing south-westerly wind direction through the year. However, there is a high frequency of north to north-east winds in spring. Topography can play a part in modifying the wind climate, as illustrated by the wind rose for Leeming. There is a tendency for the North York Moors to shelter this site from SE and easterly winds, with channelling through the Vale of York.
