A cold night in the backcountry is almost always avoidable. The fixes are simple, cheap, and mostly about what you do before bed.
There are few things more miserable than lying awake in a sleeping bag, shivering, watching the hours crawl toward dawn. The good news is that a cold night is rarely about the bag being wrong; it is usually about a handful of small habits, each easy to fix once you know them.
Start from the ground, because that is where most warmth is lost. A sleeping bag crushed beneath you provides almost no insulation, so the pad underneath you matters as much as the bag on top. On a cold night, doubling up a foam pad beneath an inflatable one blocks the endless cold seeping up from the earth, and that single change transforms the night.
What you do in the hour before bed matters more than people expect. Going to bed cold means asking your body to heat a large empty bag from scratch, which it may never manage. A short burst of activity to raise your core, a warm drink, and a snack with some fat in it give your body the fuel to run its furnace through the night.
Then manage moisture and air. Damp clothing will steal your heat all night, so change into a dry base layer to sleep in, and never bury your face inside the bag, where your breath soaks the insulation from within. A hat, dry socks, and a loosely closed hood do more than any expensive upgrade.
Swap in your own notes here: the coldest night you turned around with these tricks, the piece of kit that finally fixed your sleep, and the mistake you only had to make once. — Written by the editors.