Eastern Scotland is one of the more windy parts of the UK, being relatively close to the track of Atlantic depressions. The strongest winds are associated with the passage of deep areas of low pressure close to or across the UK. The frequency and strength of these depressions 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 high.
The variation in monthly mean speeds (average of a continuous record) and highest gusts ('instantaneous' speed averaged over about 3 seconds) at Leuchars 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 most inland areas of the region the average is around 5 days per year but places sheltered to the west experience fewer than this and well exposed upland areas have over 20 days with gale in an average year. Wind speed is sensitive to local topographic effects and land use. Exposed places on coasts and hills will experience stronger wind speeds and more days of gale. The highest wind-recording station in the UK is on Cairngorm (1245 metres) which holds the record for the highest gust (150 knots on 20 March 1986).
There have been several noteworthy gales affecting Eastern Scotland, accompanied by property damage and disruption to travel and power supplies. Examples include 13 February 1989 when the low-level wind speed record of a gust of 123 knots was set at Kinnaird's Head lighthouse near Fraserburgh (Grampian). The corresponding hourly mean speed was an equally impressive 68 knots. On this occasion, over 75,000 people in northern Scotland lost their electricity supply but fortunately there was no loss of life. More recent examples include 28 January 2002, when a severe westerly gale with gusts approaching 70 knots resulted in the closure of the Forth road bridge, and 12 January 2005 when gusts of 60 knots occurred. On each occasion, power lines were brought down and there was travel disruption.
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. The penetration of westerly winds into eastern Scotland is controlled to a large extent by topography, with the Central Lowlands assisting this but the higher ground either side providing shelter.
Spring time tends to have a maximum frequency of winds from the north east. This seasonal effect is due to a build of high pressure over Scandinavia. In Eastern Scotland, periods of very light or calm winds with no preferred direction vary from about less than 1% of the year on the coast to about 5% at sheltered places well inland. The annual wind rose for Leuchars is typical of open, level locations across the Central Lowlands, with an enhanced south-westerly wind direction through the year associated with a large-scale funnelling effect. In marked contrast, places further north, to the lee of the Grampian Mountains, experience diminished south-westerlies as air is deflected by the high ground to the west. The annual wind rose for Aberdeen airport (Dyce) is typical of this area. However, in all areas there tends to be a higher frequency of north to north-east winds in spring.
