Guide 3 min
3 or 4-season tent? The threshold is 0 C at night
No need for a 4-season tent if your night stays above 0 C. We work out your night from season and altitude, and tell you when to switch.
You'll be told a 4-season tent is "for the mountains". Too vague to decide on. The real marker is a number: as long as your night stays above 0 °C, a 3-season tent is enough. Below 0 °C, the 4-season earns its place, and not before.
The catch is that "your night" isn't the temperature shown for the valley: it drops with altitude. WildKit works it out for you. Start from your season, take off 6 °C per 1000 metres. And this same 0 °C doesn't only decide your tent: it flips your sleeping mat and your sleeping bag at the same time. Here's how to read it.
The threshold reads at zero degrees, not at the season
Most advice gives you a mood ("mountain", "winter") instead of a threshold. The result: you carry a 4-season in June to be safe, or you shiver in October thinking a 3-season goes anywhere.
Here, one number settles it. Above 0 °C at night, a 3-season holds: it protects you from wind and rain, and that's what you need. Below 0 °C, frost settles on the flysheet and condensation freezes: that's where the structure of a 4-season earns its place. It all turns on that zero.
Your night is your season minus 6 °C per 1000 metres
WildKit starts from a night temperature per season, then takes off the altitude:
| Season | Lowlands | At 1000 m | At 2000 m |
|---|---|---|---|
| Spring | 0 °C | -6 °C | -12 °C |
| Summer | 10 °C | 4 °C | -2 °C |
| Autumn | 0 °C | -6 °C | -12 °C |
| Winter | -5 °C | -11 °C | -17 °C |
Read down the column, not across the row. Spring is already right on the threshold in the lowlands: another 250 metres and you drop below 0 °C. And look at summer: at 2000 metres, your night falls to -2 °C. The season says "summer", your night says "4-season". Altitude decides, not the calendar.
The same zero flips your sleeping mat and your sleeping bag
It's not only about the flysheet. The 0 °C threshold moves two other items at the same time:
- The sleeping mat. At 0 °C or just above, a mat rated R ≥ 2 insulates enough from the ground. Below 0 °C, you need R ≥ 4: it's the cold from the ground that wakes you before the cold in the air (see the sleeping mat that holds up on a cold night).
- The sleeping bag. Below 0 °C, a mid-season bag or down jacket isn't enough any more: you go up a notch in warmth.
In other words, the moment your night drops below 0 °C, you're not swapping one item: you're changing your whole night setup. That's why the threshold matters this much.
When a 4-season really earns its place
It earns its place when your calculated night drops below 0 °C, and only then: winter everywhere, autumn or spring as soon as you climb, and even summer at altitude. As long as your night stays at 0 °C or above, the 3-season does the job. Going up a notch "just in case" protects you from nothing more that night.
What to remember
- The threshold is 0 °C at night: above it, a 3-season is enough; below it, the 4-season earns its place.
- Work out your night before choosing: your season, minus 6 °C per 1000 metres. Even summer drops below 0 °C around 2000 m.
- Below that same 0 °C, your sleeping mat goes to R ≥ 4 and your sleeping bag goes up a notch: it's a switch, not one isolated tweak.
Not sure whether your night drops below 0 °C? That's exactly what the configurator works out from your season and your altitude. Describe your trip, read your night temperature, and you'll know whether a 3-season holds or whether you need to go up a notch.
A guide WildKit keeps up to date. Published .