Do thermal clothes really work?

Thermal clothes work as part of a layering system to insulate your body and maintain a comfortable temperature. For outdoor adventures in cold conditions, a thermal base layer will trap body heat without restricting your flexibility and movement, enhancing enjoyment and performance when the temperature starts to drop.

When you are outdoors in cold weather, thermal energy is lost from the body to the surrounding air. This forces your heart to work harder, increasing blood pressure. As the body begins to cool down, you can start to experience shivering, clumsiness and confusion, eventually leading to hypothermia. Staying warm outside is essential, but large bulky clothing can restrict your range of motion and cause you to sweat heavily.

Thermal clothing is used to regulate body temperature. Close-fitting to the skin, thermal layers trap your body heat, reducing heat loss in a cold environment. Made from materials that allow airflow, they will also prevent the build-up of moisture when you start to perspire.

What is thermal clothing?

Thermal clothing is any layer worn underneath other clothing to keep you warm. A thermal base layer will trap heat close to the body and wick moisture away from the skin in low temperatures. A variety of materials can be chosen for peak performance, whatever the conditions.

Also known as base layers or thermal underwear, the phrase ‘thermal clothing’ is used for anything worn as a layer under other garments in cold weather. Effectively layered clothing usually includes three components. 

Firstly, the base layer should be lightweight, flexible and comfortable. The mid-layer adds extra warmth and insulation by trapping a layer of air using fleece or softshell fabrics. Your outer layer should be waterproof and wind-resistant.

Layering your clothing allows you to control and maximise performance, protection and comfort. The North Face guide to the world of layering explores clothing combinations for specific activities, from hiking in the rain to skiing in a snowstorm.

Choose thermal clothing that has a close fit. This will make it easier to add other layers comfortably, depending on the weather conditions. Look for lightweight, flexible fabrics that are breathable, and avoid cotton, which will absorb sweat and become heavy. 

Merino wool is a popular natural baselayer fabric, and many synthetic blends have been developed for high performance. The addition of lycra allows for added stretch when participating in winter sports.

The core of your body is the most important area to insulate. Long sleeve or short sleeve tops can be chosen based on your activity and the outdoor temperature. The North Face Women’s Easy long sleeve top is made from durable fabric to ensure longevity along with regulating body temperature. Seamless sides and gusseted underarms reduce chafing and enhance comfort.

For your legs, thermal tights, often called long johns, will help you maintain a comfortable temperature. Our Men’s warm tights are designed as a comfortable base layer for low to medium intensity activities in low temperatures. For high-intensity performance, the Men’s Pro compression tights manage moisture effectively with body-mapped ventilation to keep you dry as well as warm. 

For younger adventurers, our Boy’s On Mountain T-Shirt is lightweight and flexible. Made using FlashDry technology, the fabric is engineered to move moisture away from the skin, maintaining comfort during outdoor activities.

How does thermal clothing work?

Thermal clothing works by trapping body heat close to the skin to keep you warm. The lower the temperature, the more thermal energy will be lost from your body to the surroundings. Wearing a base layer under other clothing provides insulation to reduce the heat lost from your body.

Good thermal clothing will do two things. Firstly, trapping air close to the skin creates a microclimate around your body and reduces heat loss. 

Secondly, when you wear thermal clothing, the fabric will reduce cooling by evaporation. When sweat evaporates from the skin, it has a cooling effect on the surface. Breathable materials wick moisture away from the skin when you sweat, reducing the cooling effect. 

For over 50 years, The North Face has used innovative technology to provide the highest quality gear to modern-day explorers. Our FlashDry fabric technology allows base layers to act like a second skin. Moisture is pushed away from the body to the surface of the fabric quickly, ensuring dry comfort during strenuous activity. 

As the name suggests, FlashDry™ clothing dries quickly when wet, and garments labelled as FlashDry XD are engineered with increased resistance to tears and abrasions, offering longevity and durability. 

Thermal layers

To ensure maximum levels of enjoyment and performance for outdoor activities in winter seasons, plan your clothing carefully. Consider the conditions and the activities you have planned, consult our layering guide for advice, and you’ll be ready for anything the weather throws at you. Whether you are heading out for a winter hike, tackling the rock face or setting off to the slopes, you’ll find the right clothing for your next adventure.