I walked last year at this time--March. There was snow in Roncesvalles, Mansilla de las Mulas (just a little), Rabanal and O'Cebreiro. On the snowy days, most walked on the main road rather than the camino proper. The snow on the off road trails could sometimes be deep but the road was generally plowed. Once I'd come down from the higher elevation, and the snow was melted/less accumulation, I'd rejoin the camino proper. I found it was a great time to walk--the snow days (and some others) were a little cold but also there were sunny, warmer days which were very pleasant. I had one pair of gore tex trousers which were useful on the snowy days but otherwise wore very thin quick dry trousers (with silk long underwear on colder days), a fleece jacket --on the coldest days with a layer of silk undershirt, regular quick dry shirt, lightweight wool shirt and a rain coat. I also had a fleece cap and lightweight knit gloves. I wore wool socks. I felt warm enough even on the cold days. I hope they enjoy this time of year--I certainly did.