time of travel

When

I did the Camino during the April /May. It was beautiful seeing the flowers bloom. The refugios were not crowded in the beginning and they were not worn from the heavy summer traffic. In addition about the 5th of May there is a big party in Santiago for Ascension day. It is quite a public celebration and a fitting end to 33 days on the Camino.

I am doing my second Camino August/September and am hoping to see a different season.

not many people walk in november and december. if you want a more solitary experience, this is the time to go
you meet fewer people but get to know them better
you never arrive at an albergue too late to get a bed, but some albergues are closed in the winter so you might have to walk a little farther to get to the next one
dawn is later and dusk is earlier so you have fewer hours to walk during the day
and, as you say, the cold isn't that bad, but the mud is. it's pure clay, it builds up on your boots as you walk and it's very very slippery