In winter, the nights are longer. Darker. All the more time for your outdoor sleepover! A winter adventure – whether a multi-day trip or a school-night microadventure – can be a refreshing antidote to winter blues.
Yes! When you bivvy in winter, you don’t need to share the stars. Under the huge dark sky, the outdoors is all yours. The Milky Way, the planets, the birdsong, and the silence. You can take winter in from the ultimate cosiness of your sleeping bag. It might just take a little more preparation!
There are four main ways in which you lose heat while bivvying in the winter: convection, conduction, evaporation and respiration.
Convection is when that lovely warm air next to your body really wants to move to the cold air outside your bivvy. The solution? Trap it!
Keeping your kit dry and clean is vital. Not only does wet kit conduct heat away from your body more quickly, but your down jacket and sleeping bag won’t keep you as warm if they’re damp and dirty. A dry bag will never go amiss. And if you’re sure you’re going to be sleeping out in the rain, a synthetic fill sleeping bag might be a safer bet than down due to its performance in both wet and dry conditions (the weight penalty is worth it!).
In winter especially, the ground will also conduct heat away from you. A thick, insulated sleeping mat, like the Dozer or the Dirtbag, is essential not only for comfort but also for warmth. You could also use natural materials – such as spruce boughs to improve the comfort and insulating abilities of your sleeping mat.
Evaporation very effective at getting rid of heat. This is great when it’s a warm, sunny day and we sweat to cool down. But this isn’t so great when you’re bivvying in the dead of winter. In fact, the body can lose up to 350ml of water during an 8-hour sleep. To prevent heat loss through evaporation, prevent as much environmental moisture as possible from getting into your sleep system. Put simply, don’t let the snow in. And to prevent extensive sweating overnight, try not to get in your bivvy cold in case you later overheat, sweat and cool down.
It might seem tempting to snuggle up inside your sleeping bag to keep your face out from the cold. However, the moisture in your breath will condense and cause damp patches. If your sleeping bag has a down fill, this will negatively affect its insulating properties. And make you colder. What to do instead? Buy a beanie and breathe outside your bivvy.
Our packing list for a winter sleepout includes: