Wednesday 16 June 2010, 12:10
We've had more than our fair share of north-east winds so far this year which led to a cold winter in Wales followed by a dry spring with rainfall below the long term average.
During the spring and early summer north-easterly winds are fairly common in this part of the world. The jet stream weakens and areas of high pressure form over the sea. However, the weather pattern often breaks down in mid to late June when we often see the 'return of the westerlies'. Some people call this the start of the 'European Monsoon'.
The jet stream strengthens and moves north towards Iceland steering low pressure systems in the Atlantic towards Scotland. These bring spells of rain to northwest Europe and the downpours can play havoc at Wimbledon and turn the Glastonbury Festival into a mud bath. Once a weather pattern is set it can be difficult to shift and can continue for the rest of the summer.
However, the European monsoon normally weakens in July and if we are lucky the rain is interspersed with areas of high pressure from the Azores which bring us spells of warm and settled weather. These may last a week or two but more often than not, the most we can can hope for is three fine days followed by a thunderstorm.
After such a cold winter you may think we deserve a hot summer this year which was the case in 1947. Given the law of averages this summer should be better than the last three but of course there are no guarantees. The word 'changeable' comes to mind so keep the brolly handy for when the heavens open and make the most of the good days.