Today I looked out in my bantam run and my silkie and her two silkie chicks were out in the snow looking miserable. It has a roof, but the run isn't very wide, so the snow can blow all the way across. Not sure if they were out there because they wanted to be or because the bantam cochin and her chicks weren't letting them in to the coop. I put them in the coop then took them out one by one to blow dry them. Yes, now I can add "blow dried a chicken" to my life's accomplishments. They actually seemed to like it which surprised me. I also stuck a card board box out in the run so they'll have shelter if this happens again.
So for you with silkies, how wet do they need to get before they need intervention? These ones had wet outer feathers, but their under feathers still seemed to be dry.
Also, I am never ever having two broodies in the same coop at the same time again. Nothing but drama.