When it comes to staying dry and at the right temperature when trekking, there's no use in just multiplying the number of layers: you just need to find the right combination of clothes!
The 3- or 4-layer rule is a heat management and humidity regulation technique that involves switching up clothing combinations based on the weather conditions and the intensity of the physical activity.
Joel and Astrid, mountain guides in Chamonix, explain how you can master this must-have technique for outdoor sports.
When you do mountain sports,whether it's summer or winter, you always need to have the right kit to handle three key elements:
- Body heat: Protecting yourself from the cold and avoiding overheating.
- Weather: Rain, wind, snow, and UV rays.
- The intensity of the activity: physical activity increases your body temperature and causes you to sweat more, which can soon become uncomfortable if it isn't wicked away properly, as you may get cold in your wet clothes as the intensity of the activity decreases.
Successfully layering 4 layers thus allows for sweat to be evacuated and wicked away from the body thanks to a breathable layer, for body heat to be retained or distributed through the adaptation of insulating layers, and for you to be prepared for any weather changes thanks to a protective layer.
While people tend more to talk about the "3-layer technique" in the hiking and trekking worlds, we prefer recommending the 4-layer technique. Of course, when you're on an adventure over multiple days, you'll be exposed to a higher chance of weather changes!
That said, remember: you don't always need to set off with 4 layers in your bag! It's important to adapt your kit to the weather conditions, your personal preferences (weight, comfort, etc.), and your body (level of sweat, tolerance of the cold, etc.).
For further details, you can refer to the full kit list that we recommend for trekking, as well as our bivouac checklist.
The list of clothes advised by Joel and Astrid, mountain guides:
Layer 1: Long-sleeved T-shirt in merino wool
Layer 2: Base layer jacket in merino wool and synthetic fibres
Layer 3: Quilted down jacket
Layer 4: Waterproof and windbreaking jacket
Their top tips for adapting layers during a trek in cold weather:
- If the weather is mild and sunny, only wear Layer 1 for the ascent.
- If the weather is cold, wear Layer 2 for the ascent and descent.
- Only wear Layer 3 for the bivouac or during breaks. Downs and quilting aren't great with humidity, so avoid wearing your down jacket in the rain or when you're sweating a lot.
- Wear Layer 4 in wind or rain. You can even wear it when it's warm and/or during an ascent, as long as you open the zips underneath the arms to evacuate any humidity.
Joel and Astrid recommend:
Layer 1: Short-sleeved T-shirt in merino wool
Layer 2: Thin down jacket
Layer 2 or 3: Softshell jacket
Layer 4: Waterproof jacket
Their top tips for adapting layers during a trek in warm weather:
- Only wear Layer 1 for the ascent. If you like, you can add the softshell jacket if the wind picks up or you start to get chilly.
- Once again, don't wear the down jacket for the ascent, you'll risk overheating and ending up wet from sweat (and then getting cold once you stop).
- The softshell can be worn as Layer 2 (in warm and windy weather) or as Layer 3 over the down jacket (if you're really cold).
- Wear Layer 4 if it rains and, if you feel like you're starting to sweat, don't forget to open up the ventilation zips under the arms to evacuate any humidity.
Now you know how to dress to stay warm and dry on the mountain trails. All that's left now is to get your backpack ready and pull on your trekking boots!