I walked the Primitivo in June and it got quite hot so need to start early; wear a hat; and carry at least 2.5 litres of water on the more remote days as there is nowhere to top up. When I walked the Salvador in May there was snow on the ground but after an hour walking up hill with a pack you won't be cold.
Wow, so different from my experience in July. Guess that this just reinforces what we already know, that there are really no “normals” anymore.
As far as snow and possible danger from walking on the Salvador (btw, I don’t think this is an issue on the Primitivo). The highest parts of the Salvador are after Poladura and before Arbas. But there is some good elevation between Buiza and Poladura as well.
Though I usually don’t recommend “talk to the locals,” since they frequently just send you to the highway and have no idea about the camino route, in this case, speaking with the albergue hospitaleros in La Robla and Poladura is a very good idea if there is any chance of snowfall or snow already there on the mountains. Also, Ender runs the Salvador facebook page and answers very quickly. He knows the mountains in this area like the back of his hand and will not steer you wrong. He also makes frequent trips from his home to both places to see who’s there. So if you stay in La Robla, make sure to raise the window shade in the kitchen — that’s the way he makes a guess as whether he should stop or not.