The WORLD GUIDE says:
"Northern Europe lies in the westerly wind zone between 40° and 60° North, whereas the south is influenced by the subtropical high pressure belt. As the global weather machine migrates south for winter from its northern summertime position, European weather patterns also shift with the changing of seasons. In summer, approaching Atlantic low pressures track way up north, minimising the wind yield in Northern Europe. The likelihood of summertime wind is highest in Ireland, Scotland, Denmark and West Scandinavia; Cornwall and Brittany markedly lose out on strength and frequency as they’re often under the influence of the Azores High. In contrast, Portugal profits from... "