Walking in winter I always carried basic rations since the only shop or bar in town may NOT be open during the off season! My basics include tea bags, packets which make a cup of soup (even including croutons), firm cheese, small sausage, simple cookies and some chocolate. Often these same ingredients serve as a predawn breakfast hours before any Spanish bar would dream of opening.
Any season can be a wonderful time to walk, but in winter you MUST be prepared for varied weather. Nights can be extremely cold with freezing rain or snow. Learn to read the sky for possible storms, ask locals for advice and take every precaution.
In bad weather many steep descents on the Camino Frances would be treacherous and following smaller parallel roads might be necessary. Winter 2012/13 the Napoleon route from SJPdP to Roncesvalles was filled with several meters of snow and in effect closed to pilgrims thus necessitating the use of the Valcarlos alternate; read more here about this recent hazardous situation. During summer 2015 local authorities have decided that the Napoleon route will be closed from November 1 to April 1. Read more here.
Other difficult stretches after storms might be from Najera to Santo Domingo de la Calzada or across the Montes de Oca from Villafranca as well as Monte Irago and, of course, O Cebreiro.
Not all albergues will be open, but the welcome at those albergues which are is often most sincere. Most will usually be heated and/or have blankets. Generally the hospitaleros know who is open on the next stage. A new list of albergues Open in Winter should be available as a 2018/2019 Forum resource.
When walking in late autumn/winter only in larger places such as Roncevalles, Logrono and Santo Domingo de la Calzada and, of course, Santiago have I ever seen a cluster of more than 20 pilgrims at one time. It is easy to walk alone and in smaller albergues you might be the only pilgrim.
Twice during winter caminos I have sat out true blizzards; in Villafranca Montes de Oca, February 25, 26, 2006 and Foncebadón, March 5,6, 2009. Even late November 2012 the climb up to O Cebreiro was packed with snow. You can see the snow and read my blog accounts of these three memorable storms here. Luckily open albergues offered welcoming shelter, heat and companionship.
In cold weather periodic bar stops throughout any walking day are necessary for a warm seat, coffee, hot chocolate or fresh orange juice and the loo. In Léon hot chocolate is so thick that the spoon almost stands in the cup. Served with freshly made crullers it is a delicious, caloric treat and fuel for trekking! For another delicious pick-up try freshly squeezed zumo naranja or orange juice. No champagne has ever tasted better!
Most of us who walk in late autumn and winter wear and carry lightweight but warm layers which can easily be added or removed while walking. Each pilgrim develops a favorite combo. Scan the Forum's Equipment topic to see a multitude of varied approaches. Here's mine
What a great reply Mspath, I found it very helpful also, I'm planning on walking through December. I have provisionally booked a flight into Biarritz on the 21st November. (Although this could change due to work commitments). Wishing you a safe walk bubble.