Last year we bivvied on snow on a glacier in Austria summer at 2750m. Wind came in and it got pretty chilly - started snowing so I guess it was around zero with some wind chill. Three nights little sleep, cold "creeping" up from the snow but also extremities. Not fun! When sleeping on rock at same altitude it was much warmer.
Gear was, Rab Neutrino 200, Thermarest Z-lite matt and alpkit bivvy bag. Plus I was wearing Montane Smock and climbing trousers and hat in the bag. Usually I am not a cold person. Aware the bag was a little lean for the conditions but didn't expect to be that chilly.
This September we are going to be camping at about 3300m in French Alps. We are bringing a tent (Mountain Hardware Ghost UL2) with give us more shelter but will that be enough to stave off the cold? Have an foam/inflating matt combo which I think would be warmer but would a new bag be the way to go? What about some Scottish Winter style base layers?
Thanks!