Quick answer: a snow shelter works because snow is mostly trapped air, which insulates well. The easiest for most campers is a quinzhee: pile and mix snow into a dome about 6 to 8 feet tall, let it settle and harden for a couple of hours, insert sticks about 12 inches long as thickness guides, then hollow it out until you reach the sticks. Make the entrance lower than the sleeping platform, poke a vent hole, smooth the ceiling so it does not drip and never run a stove or heater inside without strong ventilation. Build with a partner, keep a shovel inside and avoid slopes where avalanches are possible.
Snow shelters are a classic winter skill. A well-built quinzhee or snow cave can feel surprisingly calm and quiet compared with a tent flapping in the wind. They also take time, energy and some care to build safely. This guide is part of our winter camping guide and is meant for campers who want to practice snow shelters on a planned trip, close to a trailhead or with a tent as a backup.
Information is drawn from winter travel instruction published by outdoor education organizations, national park and forest service winter safety guidance and avalanche education centers. Snow conditions vary widely, so practice in safe terrain with an experienced partner before relying on a snow shelter. This is general information, not a substitute for hands-on training.
Why Snow Shelters Stay Warmer
Fresh snow can be mostly air by volume, and that air is held in small pockets that slow heat loss. A thick snow wall blocks wind completely. Inside a well-built shelter, the air often stays near the freezing point even when it is much colder outside, and body heat warms it a little more.
That does not make a snow shelter warm in the indoor sense. You still need a winter sleeping bag and an insulated pad, because the floor is snow. Our guide to the winter sleep system explains how R-values and bag ratings work together.
Types of Snow Shelters
| Shelter | How it is built | Snow needed | Time and effort | Best use |
|---|---|---|---|---|
| Quinzhee | Pile snow, let it harden, then hollow out | Any snow that can be piled; works with fluffy snow | Several hours with two people | Planned trips, practice and groups |
| Snow trench | Dig a trench, cover with a tarp, skis or snow blocks | Firm snow at least a few feet deep | Fastest option | Quick shelter or emergencies |
| Snow cave | Dig into a deep, firm drift | Deep, consolidated drifts | Hard work, wet clothing risk | Where natural deep drifts exist |
| Igloo | Cut and stack blocks in a spiral | Wind-packed snow that holds as blocks | Skill and practice | Open, wind-packed areas |
Quinzhee
Quinzhees are the most forgiving shelter for beginners. Because you create the snowpack yourself, they work in many places where snow is not deep enough to dig a cave. The trade-off is time; piling and hollowing a two-person quinzhee can take several hours.
Snow Trench
A snow trench is a narrow trench a little longer than you, with a roof made from a tarp, branches or snow blocks. It is quick and uses little energy, making it a common emergency shelter. It is colder than a dome, but it gets you out of the wind.
Snow Cave
Snow caves are dug into deep drifts, often on the lee side of ridges or banks. That location is exactly where snow piles up on slopes, so check avalanche terrain carefully. Digging also soaks clothing, which can be dangerous in the cold.
Igloo
Igloos need snow that can be cut into strong blocks. In the right conditions, a practiced builder can make one efficiently, but most beginners find the technique takes repeated attempts.
Choosing a Safe Spot
- Avoid avalanche terrain. Stay off and away from the bottoms of slopes steeper than about 30 degrees and out of gullies where snow can slide. Our guide to avalanche safety for winter campers explains how to recognize risky terrain.
- Look up. Avoid spots under dead trees or heavy snow-laden branches.
- Choose flat ground with enough room to pile snow in a wide circle.
- Check for hidden hazards such as streams, boulders or thin ice beneath the snow.
- Stay near your route and a reasonable distance from the trailhead for your first attempts.
How to Build a Quinzhee Step by Step
1. Mark the Base
Stamp out a circle about 8 to 10 feet across for two people. A larger base gives you more room inside, but it means much more snow to move.
2. Pile the Snow
Shovel snow into a mound 6 to 8 feet tall. Mix layers of snow as you go rather than piling only one type, because mixing helps the snow bond. Some builders pile snow over packs or a tarp-wrapped heap of gear to save effort, then remove it later; others keep it simple with solid snow.
3. Let It Sinter
Leave the pile alone for a couple of hours. During this time the snow crystals bond and the pile hardens, a process called sintering. Colder, drier snow may need more time. Use the wait to set up a backup tent, cook or collect sticks for the next step.
4. Insert Thickness Guides
Push sticks about 12 inches long straight into the dome all over its surface. When you dig from inside and hit the end of a stick, you know the wall is about a foot thick. Walls around 12 inches thick are a common target.
5. Dig the Entrance
On the downwind side, dig a low entrance tunnel. Keep it small and below the level of your planned sleeping platform. Cold air sinks and will drain out the entrance, leaving warmer air above.
6. Hollow It Out
One person digs inside while another clears snow away from the entrance and keeps watch. Dig upward and outward, shaping a dome-like ceiling. Stop at the sticks. Leave a raised sleeping bench higher than the entrance if you can.
7. Smooth the Ceiling
Smooth the inside walls into an even curve. Bumps and points become drip spots as the shelter warms.
8. Add a Vent
Poke a fist-sized hole through the roof, at an angle, with a ski pole or stick. Keep it clear through the night by checking it regularly.
9. Mark the Shelter
Mark the outside with wands, poles or skis so nobody walks or skis on top of it.
How to Build a Snow Trench
When time or energy is short, a snow trench is the fastest way to get out of the wind. It works best in firm snow at least 3 feet deep.
- Mark a rectangle a little longer than your body and about shoulder width.
- Dig straight down about 3 feet, keeping the walls vertical. Pile the removed snow on the upwind side as a windbreak.
- Cut a lip along the top edges if you plan to lay blocks across, so they have a ledge to rest on.
- Build the roof with a tarp weighed down by snow, skis and poles covered by a tarp, or snow blocks leaned together in an A shape.
- Leave one end open or partly covered as an entrance and air vent, ideally downwind.
- Insulate the floor with a foam pad and an insulated air pad, plus your pack under your legs.
A trench is colder than a quinzhee because it has less snow around you and a thinner roof, but it uses far less energy. In an emergency, saving energy and staying dry matter more than comfort.
Spending the Night Inside
Once the shelter is built, a few habits make the night safer and more comfortable.
- Change into dry layers before you get cold. Building a shelter makes most people sweat.
- Bring in only what you need: sleeping bag, pads, water bottles, headlamp, shovel and a few snacks. Store the rest of your gear just outside, marked so you can find it.
- Keep water bottles inside your bag or wrapped in clothing so they do not freeze.
- Light a candle lantern only with care and only if your vent is clear. Some winter campers use the flame as a rough warning: a dimming flame can be a sign of poor air, but it is not a reliable carbon monoxide detector.
- Brush snow off before you crawl in, so you do not melt it inside on your bag.
- Keep the entrance clear. If it snows overnight, check that drifting snow has not sealed it.
- Plan for a cold exit. Leave boots in a stuff sack inside your bag or in the shelter so they are not frozen solid in the morning.
Ventilation and Carbon Monoxide
Carbon monoxide can build up quickly in a snow shelter, especially if snow blocks the vent or the entrance. Avoid cooking inside a snow shelter. If you must use a stove in an emergency, keep the entrance and vent open and use it for the shortest possible time. Never run a heater or burn fuel inside while you sleep. Headache, nausea, dizziness and confusion can be signs of carbon monoxide poisoning; get everyone outside into fresh air immediately.
Breathing alone also humidifies the air and can glaze the inner walls with ice, reducing airflow through the snow. A clear vent is essential.
Collapse and Other Safety Risks
- Never build alone. Have a partner outside while digging.
- Keep a shovel inside the shelter so you can dig out if the entrance fills.
- Watch for thin spots. If you see light glowing through the wall during the day, that spot is probably too thin.
- Do not let anyone climb on the roof.
- Avoid building in warm, wet conditions when the dome may slump.
- Stay dry. Wear a waterproof shell and swap to dry layers once the shelter is built. Wet clothing raises the risk of cold injuries; see our article on hypothermia and frostbite for warning signs.
Gear for Snow Shelter Camping
- Avalanche-style metal shovel, ideally one per person
- Saw for cutting blocks, if building trenches or igloos
- Waterproof shell jacket and pants, plus spare gloves
- Closed-cell foam pad and an insulated air pad
- Winter-rated sleeping bag
- Headlamp and spare batteries kept warm
- Ski poles or sticks for vents and thickness guides
- Wands or poles to mark the shelter
- A backup tent for your first trips
Our winter camping gear checklist covers the rest of a winter kit.
Practicing Before You Rely on It
Most experienced winter campers recommend practicing snow shelters close to home or a trailhead before depending on one. A backyard or a nearby park with deep snow can work for a first quinzhee. Build one in daylight with plenty of time, then decide whether to spend the night inside. Many first-time builders sleep in a tent next to their quinzhee the first time and use the shelter only for a few hours to get a feel for it.
Leaving No Trace
When you leave, knock down the shelter if land managers recommend it, so nobody falls through a weak roof later. Pack out all trash, and avoid cutting live branches for roofs or bedding.
Frequently Asked Questions
How long does it take to build a quinzhee?
Plan for several hours with two people, including time to pile the snow and let it harden. Larger shelters take longer.
How thick should quinzhee walls be?
About 12 inches is a common target. Insert sticks of that length into the dome before digging and stop when you reach them.
Is a snow shelter warmer than a tent?
Usually yes. Snow blocks wind and insulates, so the air inside often stays near freezing even when it is much colder outside. You still need a winter sleeping bag and pad.
Can I cook inside a snow shelter?
It is best not to. Stoves can produce carbon monoxide, and snow shelters can trap it. If you must, keep the entrance and vent fully open and limit burn time.
Do I need special snow to build a quinzhee?
No. Quinzhees work with many kinds of snow because you pile and mix it yourself and let it harden. Igloos need firm, wind-packed snow.
What is the quickest emergency snow shelter?
A snow trench, covered with a tarp, skis or snow blocks, is usually the fastest to build and gets you out of the wind.
