Last August, above Lac Foréant in the Queyras, I pitched my tent above 2,400 metres for the first time. It was still light when I reached the grassy shelf overlooking the lake; two hours later, the temperature had dropped from 14°C to 3°C and the wind had picked up all at once, the way it often does at the end of the day when cold air off the summits sinks into the hollows below. It's that sudden swing, more than the altitude itself, that sets a mountain bivouac apart from a night at a campsite.
Gear: what actually matters
Choose your sleeping bag by its comfort rating, not the "limit" temperature printed on the label — that figure marks the edge of survival, not a decent night's sleep. Simple rule: pick a bag with a comfort rating at least 5°C below the coldest night you expect. In the Queyras in August, at 2,400 m, plan on lows around 2 to 5°C, which makes a 0°C comfort-rated bag a reasonable minimum.
Your sleeping mat matters just as much as the bag: it's what cuts off heat loss to the ground through conduction, which drains far more warmth than the surrounding air ever will. An R-value above 3 is essential once you're bivouacking above 2,000 m, even in summer.
A realistic weight budget for a 3-season sleep system (bag, mat, and a one-person tent or bivy) sits between 1.3 and 1.8 kg. Go much heavier than that and it starts to cost you over a multi-day route.
Choosing your spot
Three criteria, in this order of priority:
- Wind: look for a rock outcrop or a dry-stone wall to shelter you from the prevailing wind. Steer clear of passes and open ridgelines.
- Overnight cold: cold air flows downhill and pools in hollows. A gentle shelf, neither at the bottom of a valley nor exposed on a ridge, keeps this in check.
- Storm risk: stay well away from ridgelines and isolated high points, and never camp at the bottom of a gully if storms are forecast — flash flood territory.
"Sleeping outdoors means accepting that, for one night, the mountain decides the room temperature."
Regulations: check before every trip
In most French national parks, lightweight bivouac (a single tent, pitched after and struck before a set time window, no fires) is tolerated in the core zone if you're more than an hour's walk from the park boundary, typically between 7pm and 9am.
But these rules shift from one range to the next — national park, regional nature park, nature reserve — and change over time, particularly around wildlife protection periods. Your best bet is to check the official website of the park or reserve in question, or ask the local tourist office, in the days before you head out rather than rely on a general rule.
If a storm hits during the night
This is the scenario few articles cover, even though it's the real safety question in high-altitude bivouac: before dark, identify a lower, less exposed fallback spot (no more than 15-20 minutes away on foot), keep your boots and headlamp within reach without having to dig through your whole pack, and never stay in your tent if you're on a ridgeline or near an isolated summit once the storm breaks. The mountain emergency number remains 112 anywhere in the European Union, reachable even with no signal from your own carrier.
Morning, and the ethics of the place
The morning ritual is also about respecting the place: pack up before other hikers arrive, leave no trace on the ground (including cigarette butts and fruit peels, which take months to break down at altitude), and check that no litter was left behind under the rocks that held your tent down.
Checklist before you leave
- Weather forecast for the day before, plus storm risk for the night itself
- A sleeping bag suited to the conditions (comfort rating ≥ 5°C below the forecast low)
- A sleeping mat with R-value ≥ 3 if altitude > 2,000 m
- Bivouac regulations for the range checked on-site or online
- A fallback spot identified in case of storm
- Headlamp and boots accessible without unpacking your bag
- A bin bag to carry all your rubbish back down