Adding a layer of thermal underwear to your winter ensembles can make a significant difference. This extra layer of warmth, which can be obtained in insulated leggings or a thin, insulated blouse, is meant to be worn under an outer layer.

Wool, silk, and synthetic materials are widely used in thermal layers because they are all excellent at wicking away moisture, trapping heat inside, and drying quickly.

9 Best Cold Weather Under Clothing

1. Smartwool Intraknit Merino 250- Best Thermal Bottom

Smartwool Intraknit Merino 250- Best Thermal Bottom


The merino wool structure may seem standard these days, but Smartwool’s Intraknit design offers it a tech-focused boost. These leggings are woven with terry loops and mesh to assist in ventilating and insulating at the same time.

If you’re looking for a pair of thermal underwear that will keep you warm no matter what you’re doing, this pair from Smartwool is a good choice. These leggings also include a ribbed knee, which adds to their durability and flexibility.

2. TSLA Thermal Underwear Set

TSLA Thermal Underwear Set


Although microfiber won’t keep you warm in the outdoors, finding a set that can serve you well in various scenarios at a low price is a win and a smart item to have in your cold-weather layering arsenal.

This moisture-wicking, fleece-lined long-sleeve shirt and legging pair is available in 12 colors. This best cold weather underclothing has a lot of elasticity, making it a fantastic alternative for folks who work all year outdoors and require an extra layer. A women’s version of this set is also available.

3. Best Leggings (Men): Salomon Essential Wool Tight

Salomon Essential Wool Tight


The natural capacity of merino wool to keep odor at bay makes these wool tights from Salomon ideal for outdoor sports. These tights have a slim fit and should be worn with a layer or two underneath. The material is very breathable, which is important for anyone who is going to be active outside.

4. Best Leggings (Women): Arc’teryx Rho LT Bottom

Arc'teryx Rho LT Bottom


Arc’teryx’s Rho leggings are a pair of lightweight leggings that are surprisingly warm. This best cold weather underclothing is a terrific alternative for skiing and snowshoeing in the winter and climbing or trekking in the summer when worn under another garment.

There’s a built-in brushed lining that adds to the comfort and softness of these. For colder days, these leggings are thick enough to wear without a top layer.

5. Best Thermal Set: Thermajane Ultra Soft Thermal Underwear Long Johns Set

Thermajane Ultra Soft Thermal Underwear Long Johns Set


The long thermal john set from Thermajane is fleece-lined and oh-so-soft. This odor-resistant combination, which includes a long-sleeve shirt and leggings, features a particular four-way stretch that allows you to move comfortably in any direction (great for skiing or any sport that can send you bending in weird positions).

This thermal underwear set comes in 12 colors and is perfect for relaxing around the home as well as keeping you toasty under all of your outdoor gear. A men’s version of this thermal ensemble is also available.

6. Best Wool: Icebreaker 175 Everyday Leggings

Icebreaker 175 Everyday Leggings


These wool leggings are form-fitting and tight around the ankles, making them the ideal base layer for winter sports aficionados. They can be worn casually, but those who put them to the test on a hike, in the mountains, or with some alpine climbing will get the most out of them.

The seams are kept to a minimum to prevent chafing, and the men’s design has a functional fly for added convenience.

7. Best Lightweight: Ortovox 185 Rock’N’Wool Long-Sleeve Top

Ortovox 185 Rock'N'Wool Long-Sleeve Top


From its odor-resistant merino wool to its excellent temperature management, Orotvox’s Rock’N’Wool shirt was designed for outdoor use. If you’re looking for a splash of color, you’ve come to the right place.

This lightweight, long-sleeve best cold weather under clothing comes in three vivid colors and patterns, contrasting to most thermal underwear and its ever-neutral palette. The women’s version of this thermal top is also available.

8. Best for Layering (Men’s): Smartwool Merino 250 Base Layer

Smartwool Merino 250 Base Layer


These leggings are no exception to Smartwool’s reputation for reliable fundamentals. The Merino 250 Base Layer is made of midweight Merino wool and has a flat-lock seam to prevent chafing.

The leggings include a classic fly and all of the benefits of merino wool (odor resistance, temperature regulation, and softness).

9.Best for Layering (Women’s): 32 Degrees Base Layer Thermal Leggings

32 Degrees Base Layer Thermal Leggings


This 32 Degrees baselayer feels as if you’re not wearing anything at all (in the best way possible). The polyester fabric is brushed on both sides and is extremely pleasant to the touch.

This best cold weather underclothing is invisible—in the nicest way possible—with four-way stretch and an elastic waistline, making it ideal for sliding on underneath a pair of hiking pants, snow pants, or jeans. If you’re wearing them alone, keep in mind that the thinness of the fabric, while warm, can be a little see-through.


If you don’t mind spending a little money, the Smartwool Intraknit Merino 250 Thermal Bottoms are a good option. This legging is available in both men’s and women’s fashions and performs an excellent job of insulating and ventilating.

If you’re searching for a low-cost pair to wear around the house or in less stressful situations, the Thermajane Ultra Soft Thermal Underwear Long Johns Set is a wonderful option, as it includes a thermal t-shirt and leggings for a reasonable price.

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