Important for excursions of any kind into mountains anywhere, the weather forecast has to be the first thing to check. Here are the best weather information sites, widgets and webcams for the Picos de Europa that we've found.
This first one is a link for the weather forecast for the Cantabrian mountains - https://www.infonieve.es/meteo/cordillera-cantabrica/
This next live feed is for weather conditions around Potes, the main town of Liébana in Cantabria.
Indispensable for checking winter snow conditions

View detailed snow forecast for Picos De Europa at:
snow-forecast.com
And one from Meteored.com, a highly interactive Spanish weather site with great photos and a busy forum. This prediction is for Cabrales in Asturias including the north end of the Cares gorge.
Here's one for the Atlantic coast, based on the beach near San Vicente de la Barquera. Check the surf conditions
Surfforecast

View detailed surf forecast for Playa de Meron. Visit surf-forecast.com for more details, long range forecasts, surf reports, swell and weather maps.
Finally, a link to the webcam at Fuente De, the only cable car in the Picos, rising to the Central Massif in Cantabria - handy for checking out cloud base levels during inversions too.
Note, the image below is not live!