We need to talk about the weather. Pyrenean weather is fluid and in constant motion. The two abutting bodies of water—the Atlantic Ocean to the west and the Mediterranean Sea to the east are significant factors in the climate. At the western end of the Pyrenees, the Atlantic weather systems prevail, and rainfall is high. The Basque Country in the SW corner of France is one of the wettest areas in the country. As you move east, the rain levels fall, and the weather becomes drier and sunnier.
The atmosphere is incredibly moist, and the contrast in humidity between the French and Spanish sides of the Pyrenean mountain range is considerable. This makes for wild variations in local weather patterns, which change quickly in different directions and at various altitudes. It can be raining at 500 meters but brilliant sunshine above the clouds at 1000 meters. The interaction between the sun's rays and localised moisture levels creates valleys full of clouds and mountaintops basking in the sunshine.
So a rule of thumb is to get up high if it is raining where you are.
