february bivvy on the horizon.
-15 sleeping bag, bombproof goretex bivvy bag, good inflatable mat, down longs and jacket.
would this suffice ?

It would for me Tony.

ton wrote: ↑Thu Nov 30, 2023 8:19 pm february bivvy on the horizon.
-15 sleeping bag, bombproof goretex bivvy bag, good inflatable mat, down longs and jacket.
would this suffice ?

Karl went lower than that I think and it was with a bivy system. No tent. I think he mentioned it in his blog that the temp difference would be too great from in to out.

Should be fine, I’ve done it in llandegla woods on a foam mat with a -12* rated bag in the snow Was warm enough (and I’m someone who feels the cold!)

I’ve been out in worse and survived.
Did a course in my old job that required it.

Definitely fine Tony, although you do need to be a bit more organised with kit. Most things will have frozen in a tent anyway, but it's worse in a bivy bag - shoes, bottles, water filter, electronics and breakfast all need to be inside or under the bivy bag so they don't freeze

Also might be helpful having a thin CCF mat to go under everything, just helps stop the ground from sapping any heat. I used one under my Xtherm when sleeping on snow in the Alps

No need for a bivy bag in below freezing. Snow won't melt on the bag's fabric. Been doing it like that for 20+ years. Any snow will just slide or brush off.

For the temperatures, well it depends. One may guess you're asking for a trip in England. But if you're going to Yakutia/Sakha, you'll suffer badly.

Mat is just as crucial as the bag. Make sure it's up to the temps to be expected. If not you can add a 3 mm foam mat or seek natural solutions (snow free grass/needles).

Down longs? Do you mean trousers? Why? Afraid the rating of the bag won't suffice? If you like to sit around, just drape the sleeping bag over your legs.

Snow tickles on the face. There, I've warned you!

Enjoy. With the right mindset and gear it's wonderful to sleep out in the cold.

benp1 wrote: ↑Fri Dec 01, 2023 12:16 pm Definitely fine Tony, although you do need to be a bit more organised with kit. Most things will have frozen in a tent anyway, but it's worse in a bivy bag - shoes, bottles, water filter, electronics and breakfast all need to be inside or under the bivy bag so they don't freeze

Stuff only freezes when it's damp/wet. Use a VBL sock and keep boots dry and leave them outside the bag. Also electronics, just warm them up when you wake up. If your breakfast consists of eg oats or mashed potato (flakes/powder), absolutely no need to keep them in the warmth. Stuff like bread, cheese, meat can also be warmed up in the morning. It's not like you can't cut and eat it if it's -20 °C.

benp1 wrote: ↑Fri Dec 01, 2023 12:16 pm Also might be helpful having a thin CCF mat to go under everything, just helps stop the ground from sapping any heat. I used one under my Xtherm when sleeping on snow in the Alps

a thin foam mat is great to boost a not so warm mat if you don't already have a warm enough mat.

If it's snowing just make sure your bivy is tidy, unless you like looking for your stuff under the snow first thing in the morning.