When temperatures plummet and the winter sun fades slowly behind the horizon, a mountain enthusiast has two choices: seek refuge inside a warm mountain hut or stay outdoors for the night and seek refuge in a sleeping bag. Welcome to the world of a winter bivouac! By no means reserved for hardcore polar explorers, a winter bivy is for outdoor fans can be an exhilarating experience. but only if it’s done right. The following tips will make sure you descend the mountain in a safe way.

1. Is a good night’s sleep expensive? Standard gear for a winter bivy

One of the most important items on a bivouac packing list is without question, the sleeping bag. Its comfort zone temperature should correspond to the anticipated overnight temperatures. The filling of choice is down – a synthetic sleeping bag in a comparable temperature range is much larger and heavier. However, good down sleeping bags are not exactly cheap. It’s best to go bargain hunting early. Some brands, however, also offer synthetic sleeping bags that perform impressively.

• Buyer’s Guide to sleeping bags: Down or synthetic?

If you don’t want to spend money on a new winter model right away, you can also pimp up your three-season sleeping bag a little, for example with a sleeping bag liner or a bivy sack. Both add about five degrees to the comfort temperature. Several dry(!) layers of clothing also provide additional warmth. The motto here is: More is more, but it shouldn’t be too much either, otherwise the sleeping bag’s heat retention will only work to a limited extent. With a really good down sleeping bag with a comfort range between -15 and -20 °c, it is sufficient, for example, to combine long underwear with a mid-layer and simply slip into the sleeping bag.

Another essential feature is a winterproof sleeping pad. Inflatable mats with an R-value higher than four have proven to be ideal. The R-value corresponds to the insulating effect of the mat. Rule: Thicker is warmer. The insulation effect of the entire pad can be slightly increased by placing jackets, a rope or a tarpaulin underneath.

2. Making a nest – sleeping outdoors

One of the biggest advantages of bivouacking in winter is the construction of your shelter: No flat surface on the slope? Not a problem, a platform in the snow can be quickly created using a shovel. No wind protection? A few blows with a shovel and the wall is up! A storm is brewing? A neat cornice offers space for a whole one-room dwelling. A winter wonderland brings out the home builder in just about anyone.

The least protection against the elements is provided by an open-air bivouac. For a reasonably cosy night, you first need to trample the snow with your skis and protect the site against the wind by erecting walls. A breathable bivy sack such as the Rab Neutrino 800 is standard gear. A ground tarpaulin helps keep moisture out.

An igloo or snow cave is a more comfortable option: this white gold is an excellent insulator and protects against wind and snow. Which type of dwelling you choose depends on the nature and quantity of the snow and the terrain. The snow cave has proven particularly popular in alpine areas, as it is much faster and easier to dig.

When building and using a winter bivouac shelter, you should also consider these 5 useful tips:

• Leave cold outside: Ideally, the entrance to a snow cave should be below the sleeping area so that cold air can “flow off”. In an igloo, you dig a small trench in which the cold accumulates.

• Provide ventilation: A few small holes in the roof are not enough: they close up too quickly. It is better to leave the entrance a little open. In adverse weather it has to be cleared several times a night: Without any air supply, you risk suffocating!
• Use gloves: Anyone handling metallic objects (probe, shovel) should always wear dry, warm ski gloves: Frostbite on the hands occurs far too quickly – and the warning signals are easily overlooked.
• Don’t sweat: If you cut your way into the snow like a mole on speed, you’ll finish faster, but you’ll also be soaked through. Wet clothes and shoes cool the body down extremely quickly and these usually won’t dry overnight.
• Cook outside: Not only does a noodle soup quickly turn a snow shelter into a stalactite cave, but cooking also produces both carbon monoxide and dioxide, which can easily collect in the cave.

Whether you decide on a roof over your head or camp under the stars, the search for a suitable spot to sleep should start much earlier with a winter bivy than in summer – this means well before dusk. This gives you enough visibility to check the slopes above the camp for the possible danger of avalanches: These white beasts also travel towards the valley at night.

3. Sleep tight – tips for a good night’s sleep

You’ve found a great spot to bunk down, your stomach is also comfortably full, now it’s time to get a comfortable night’s sleep!

Bivy professionals drain some hot water during cooking and pour it into their drinking flasks. This is placed in the sleeping bag and warms it up a bit. Second benefit: First thing in the morning you have something to drink.

• For those who have a sensitive throat, a scarf or buff is tied around their neck to protect them from sore throats and coughs. And while sleeping, a warm beanie is also a must: after all, the body loses most of its heat via the head.
• By the way: sleeping bags are often more full in the front than in the back. Meaning, if you move without turning in your sleeping bag, you won’t have a problem with the down feathers distributing unevenly. However, as soon as you the sleeping bag is turning on its side, the less full side is suddenly exposed and your back will get cold.

4. Winter Bivys – Do’s and Don’ts

• Do: Follow your urge to pee. When the bladder is full, we freeze faster, leaving an uncomfortable night ahead. In other words: one time out into the cold and then sleep through the night.
• Don’t: Leave electronics outside. If you would like to use your digicam and smartphone the next day, you should at least take the batteries into your sleeping bag.
• Do Practice. Even bivouacking has to be practised. Newcomers shouldn’t start their first winter camp at -20 degrees celsius.
• Don’t: Melt dry snow. This takes longer and may damage the pot. Better: Add a little water to the snow to improve the contact between cold snow and a hot pot.
• Do: Keep an eye on the team. Bivouac in low temperatures is a serious undertaking, despite all the fun. If a member doesn’t feel comfortable, it’s better to descend into the lowlands. This saves you a visit from the mountain rescue services.
• Don’t: Put the gas cartridge in the snow. Especially in winter many gas stoves don’t work properly because the butane-propane mixture is too cold. A trick: Use a small stand to transport the cartridge out of the snow or place it underneath. Gas stoves with gas pipes and heating spirals like the Optimus Gravity are more resistant to winter – clothing can be used to insulate the cartridge.

5. Do not disturb – respect the animal world

Animals don’t sleep as soundly in winter as some children’s books might suggest. If they are startled at night, they risk not having enough energy to survive the winter. The best thing to do is to stay close to a ski area or at very high altitudes, be quiet and use the light sparingly. This way you benefit from witnessing the stars more clearly and the animals get to enjoy their peace.