Climate

The Picos de Europa are a high mountain range separating the wet northern coast of the Bay of Biscay (also known as "green Spain") from the high dry plateau of the interior. The mountains are affected by both the continental and maritime climates. Rain is a fact of life here, and sudden dramatic changes in the weather are common. A full days outing requires preparation for all things - full waterproofs, warm clothing, sunhat, sunglasses, sun lotion, map and compass, plus adequate drinking water. Having said all this, glorious days can occur at any time of the year, and the interplays of light and cloud make the landscape even more dramatic.
 
Most rain falls in the winter and spring, leaving summer relatively dry. Hot humid summer days can lead to heavy storms though, generally in late afternoon and evening. Thick sudden mists are also common in summer, though valley mists usually burn off by midday to give a clear sunny afternoon. Snow can fall from the middle of September onwards, remaining thick on the tops until into May. There are permanent snow patches high up in hollows and lees, and some routes can be impassable until the end of June.
 
Most cold wet weather arrives from the north and west, as air laden with moisture sails in off the sea to discharge on the mountains. Areas to the south and east of the range are subject to a rain-shadow effect, making them dryer and sunnier (hotter and less green) than areas to the north and west. The valleys of Sajambre, Valdeón, and Liebana can therefore be experiencing hot weather, while the areas around Covadonga and Arenas de Cabrales will be having a cooler day more maritime in its nature. An associated effect is the "sea of cloud", which fills the northern valleys, while areas higher up are in glorious sunshine - this is actually a sign of good stable weather (worth bearing in mind if you're thinking of staying in bed having looked out of the window!).