In 2015, I walked out of SJPP on 30 September, and spent the night at Orisson. The 30th, it was so beautiful and sunny; the 1 of October, I crossed the Pyrenees walking alone, and a big storm blew in near the top. It was pouring rain, and we walked in a cloud. I saw pilgrims fade in and out of view, and three or four of us huddled at the hut and had sandwiches and shared some hot drinks; one of the gals had a thermos of hot chocolate. It was bliss.
After the pouring rain on the mountain, the clouds blew away, and the first two weeks of walking
Camino Frances was hot! I was definitely drinking a lot of water. In fact, the only time I encountered rain was in Galicia, really, and just a few days. O'Cebreiro was rainy, as I recall. No big deal.
I was not carrying a sleeping bag, by the way. At night if I was cold, I just put on all of my clothing, including wool hat and gloves, and put my poncho over the top of me (very insulating). I will mention that a lot of albergues had blankets, so that was nice too.
My pack was a 32 L and about sixteen pounds (8 kilos or so). The weather, all the way through 10 November, was just fabulous.