Faith,
Welcome to the Forum! You must be very excited as you prepare for your winter camino.
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.
Sillydoll who is a Forum member has compiled encyclopedic information on Winter Walking.
http://amawalker.blogspot.fr/2009/10/walking-in-winter.html?m=1
Other good accounts of winter walking by a Forum member Kialoa3 are his 2010 and later blogs
http://agoodwalkunspoiled.blogspot.fr/2010/?m=1
Be sure to read what others and I have written about walking in winter in this earlier Forum thread
https://www.caminodesantiago.me/community/threads/walking-in-winter.16636/
and in this thread comparing summer and winter expenses.
https://www.caminodesantiago.me/community/threads/winter-camino-expense-compared-to-summer.19699/
In bad weather many steep descents on the camino 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. Now the Napoleon route is closed to winter walking.
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. Use the handy list of open Winter Albergues
https://www.caminodesantiago.me/community/resources/winter-pilgrims-open-albergues.271/
which can be downloaded from the Resource section of the Forum.
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 FoncebadĂłn, 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.
http://mermore.blogspot.fr/p/memories.html
Luckily open albergues offered welcoming shelter, heat and companionship.
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
http://www.caminodesantiago.me/community/forums/equipment-questions.30/
to see a multitude of varied approaches. Here's mine
http://mermore.blogspot.fr/p/kit-and-tips.html
However do plan to carry some food always will you. For many summer-only shops and bar/restos will be closed. Hence my food basics include tea bags, packets which make a cup of soup (even including croutons), firm cheese, small sausage, simple cookies and some chocolate. Nothing heavy but enough to exist for 24 hours if need be. On past caminos especially during storms when I stopped in small and remote albergues far from any supply source novice pilgrims have often staggered in wet, cold and hungry. They may have had the best gear but carried no food.
Remember winter is a great time to walk, but you must be PREPARED!
Happy planning, stay safe and Buen camino!
