The Outdoor Layering System
A good layering system helps you stay comfortable outdoors by allowing you to adjust your clothing as your activity level, the weather and the temperature change.
Rather than relying on one heavy jacket to keep you warm, a layering system uses several garments that perform different jobs. Layers can be added, removed or ventilated as conditions change.
For example, when walking uphill you may generate a considerable amount of body heat. Removing a layer or opening zips can help prevent overheating. When you stop for a break or reach an exposed summit, adding an insulating layer again can help prevent you becoming chilled.
The key is flexibility. A layering system isn't static — you manage it throughout the day according to your activity and the conditions around you.
The Three-Layer System
Most outdoor layering systems are built around three main elements:
1. Base Layer — Moisture Management
The base layer is worn next to your skin.
Its purpose is to help manage moisture while providing an appropriate level of insulation for the conditions and activity.
During physical activity your body produces heat and moisture. A suitable performance base layer allows moisture to move through the fabric rather than leaving you wearing a heavy, wet layer next to your skin.
Different weights and types of base layer can be used depending on the conditions. Warmer thermal base layers are useful in colder environments, while lighter performance fabrics can be more suitable for highly aerobic activities where your body is producing more heat.
2. Mid Layer — Insulation
The mid layer sits over your base layer and provides additional insulation.
It works primarily by trapping air that has been warmed by your body, helping to reduce heat loss while still allowing moisture to continue moving away from the layers underneath.
Mid layers are available in different fabrics, thicknesses and levels of insulation, allowing you to adapt your clothing to the temperature and your activity.
In colder conditions you may use more than one insulating layer, while during strenuous activity you may remove the mid layer completely.
3. Outer Layer — Weather Protection
The outer layer provides protection from the weather.
Depending on the conditions, this may mean protection from wind, rain or snow. A suitable outer layer helps protect the insulating layers underneath while allowing moisture generated by your body to escape.
Breathability is particularly important during active outdoor pursuits. A completely non-breathable outer layer can allow moisture to accumulate on the inside of the garment, leaving the clothing underneath damp.
Why Moisture Management Matters
Staying warm outdoors isn't simply about wearing thicker clothing.
During physical activity your body produces both heat and moisture. If that moisture becomes trapped in your clothing, your garments can become damp. When your activity level drops, evaporation from wet clothing can draw heat away from your body and leave you feeling cold.
This is why the different parts of a layering system need to work together.
A simple example is wearing a cotton T-shirt underneath a non-breathable waterproof jacket during strenuous activity. The cotton can become wet with perspiration while condensation builds inside the jacket. When you stop moving, those wet layers can quickly become uncomfortable and cooling.
A well-managed layering system is designed to reduce this problem by helping moisture move away from your skin and through the layers of clothing.
Don't Forget Your Head and Hands
Hats and gloves are particularly useful parts of a flexible layering system.
They're quick and easy to put on or remove and can make an immediate difference to how comfortable you feel as conditions change.
Carrying suitable gloves and headwear therefore gives you another simple way to regulate comfort without having to change your main clothing layers.
Adjust Your Layers as Conditions Change
There isn't one layering combination that is suitable for every situation.
The right combination depends on factors including:
- temperature and weather
- wind and exposure
- how strenuous your activity is
- how long you expect to be outside
- how often you will be stopping
- your own personal preference for warmth
The important thing is to make adjustments before you become excessively hot, cold or wet.
If you're starting a steep climb, for example, removing a layer before you begin sweating heavily can be more effective than waiting until you're already overheating. Likewise, adding an insulating layer when you stop can help prevent you cooling down too quickly.
Building Your Layering System
Your layering system doesn't have to consist of exactly three garments. Think instead about the function of each layer.
Start with a suitable base layer next to the skin, add as much insulation as the conditions require, and use an appropriate outer layer when you need protection from wind or wet weather.
You can then add or remove clothing throughout the day to suit the conditions.
For more detailed information about choosing the first layer of your system, see our Base Layer Buying Guide.