The 10 Best Thermal Underwear to Keep You Warm This Winter
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Something happens this time of year, when the temperatures start to drop and the days get colder and colder. There’s a fundamental change in our brain chemistry, and we start to think differently about getting dressed each morning. At least where I live in the Northeast, it feels like I become more intentional about what I put on myself each day. And some days, depending on how cold it gets outside, my regular button-down and khakis uniform isn’t enough. Enter thermal underwear.
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As a lifelong skier, I’ve tried many—and I mean many—different kinds: merino wool, merino wool-blend, athletic compression styles, classic waffle-knit cotton, and more. Don’t make the mistake of thinking the thermals of today are the saggy, yellowing styles of yesteryear. Now, thermal underwear is sleek and form-fitting, and offers high performance. Whether you’re summiting the Alps or simply looking for some extra insulation on your commute to work, thermal underwear can make or break your level of comfort in cold climates.
And if you’re looking for the best thermal underwear for winter, here’s where to start your search. We’ve combed the market for the best available styles—from a luxe Tom Ford option for your next 007 style chase down the ski slopes to a heavy-duty L.L.Bean number for chilly weekends in the cabin.
What to Consider Before Buying Thermal Underwear for Men:
Just like so many aspects of the general underwear and performance wear markets, thermals come in several different varieties and fabrications. Here’s the essentials factors to keep in mind.
Material: Think of the material as you would a sweater. You’ll want to hit that perfect mark of warmth and breathability. Look for natural fibers such as heavy-duty cottons or merino wools if you plan on standing still or taking it easy while out in the cold. Or opt for moisture-wicking synthetics to keep you dry during periods of high exertion.
Silhouette: It really comes down to personal preference and how comfortable you want to feel. Thermal underwear as a rule is generally on the slimmer side, so it can be layered under your trousers or snow pants with ease. But there are a few specific lengths depending on the activity you have planned. Thermal underwear for skiing, for example, tends to be cropped to calf-length so the garment doesn’t uncomfortably bunch up inside a ski boot.
Best Overall Thermal Underwear
Smartwool Intraknit Thermal Max Merino Thermal Underwear
Top marks goes to this reliable Smartwool style, a 100 percent merino layer that wicks moisture, along with providing warmth and odor control. This pair is also woven with Intraknit technology, which offers insulation, a snug fit, and added ventilation. Indeed, these thermals offer warmth without making you sweat—even during high-intensity activities.
Material: Merino wool, polyamide, and elastane.
Colors Available: 1.
Most Comfortable Thermal Underwear
Mack Weldon WARMKNIT Long Thermal Underwear
You know and love Mack Weldon for their buttery-smooth T-shirts—and their thermal undies are no exception. They’re made from a ThermoLite polyester that feels positively silky to the touch and are cut in a slim fit that slips effortlessly (and undetected) under your everyday uniform. For the coldest commutes, this is your best bet.
Material: ThermoLite polyester.
Colors Available: 4.
Best Luxury Thermal Underwear
Tom Ford Cotton Thermal Underwear
Tom Ford, at this point, offers everything—including Long Johns. Nobody gets the details right better than Mr. Ford, and this Italian-made pair is a prime example. They come with a just-wide-enough elasticized waistband that never budges or folds down and banded cuffs that stay in place. Plus, it features the brand’s signature logo on the front. Who could resist that?
Material: Cotton.
Colors Available: 6.
Best Lightweight Wool Thermal Underwear
L.L.Bean Cresta Wool Ultralight 150 Thermal Underwear
As someone who has lived in a chilly climate their entire life, let me warn you: People unfamiliar with dressing for the cold tend to have this impulse to pile on as much insulation as possible. But piling on insulation often means trapping excess warmth, which can lead to trapping excess perspiration. And as soon as perspiration leaves your body, it turns frigid, which makes even the thickest thermals turn chilly in just minutes. That isn’t the issue with this classic L.L.Bean style. They’re made from a luxe, featherweight merino wool that naturally thermoregulates and never overheats.
Material: Merino wool.
Colors Available: 1.
Best Cashmere-Blend Thermal Underwear
Fusalp Allo Stretch-Jersey Thermal Base Layer
This French ski brand was founded in 1952 by two tailors from Annecy who wanted to create sleek, sexy skiwear. And boy, does that legacy continue with these thermals. They’re made from a stretch-jersey that keeps its shape all day long, and they have a seamless design for added comfort. A dose of cashmere adds an extra level of warmth, along with that particular je ne sais quoi.
Material: Viscose, polyamide, cashmere, and elastane.
Colors Available: 1.
Warmest Thermal Underwear
Arc’teryx Rho Heavyweight Thermal Underwear
When the climate calls for serious insulation, bring out the big guns. This style from the gear pros at Arc’teryx combines high-performing Polartec Power Stretch Pro fleece with a signature slim, articulated fit that hugs the leg and stays put during the most rigorous of adventures. On the inside, this fleece has a soft-brushed interior for extra comfort, and on the outside, it features a zippered thigh pocket that’s perfect for securing small essentials.
Material: Polartec Power Stretch Pro fleece.
Colors Available: 3.
Best Thermal Underwear for Skiing
Jack Wolfskin Alpspitze Wool Thermal Underwear
These thermals from Jack Wolfskin are ideal for skiing, the result of the hint of polyamide woven into the fabric. This means they stay snug around your waist as you carve turns all day long, without sacrificing any of this lightweight merino’s natural moisture-wicking and anti-microbial properties. They’re also cut in a three-quarter length for maximum comfort when worn with a ski boot.
Material: Merino.
Colors Available: 2.
Best Thermal Underwear for Outdoor Workouts
Under Armour ColdGear Leggings
These leggings double as thermal underwear that are designed for movement. They feature a wide elastic waistband that doesn’t budge, whether you’re skiing, running, or simply wearing them under your work clothes for those coldest commutes. The fabric has a flexible, comfortable four-way stretch, and the silhouette is built with a stretch-mesh gusset that (comfortably) hugs your crotch while promoting breathability.
Material: Polyester, elastane.
Colors Available: 5.
Most Breathable Thermal Underwear
Icebreaker 200 Zone Knit Merino Thermal Underwear
Knitted from a midnight merino that’s not so light that it doesn’t feel warm and not so heavy that it hinders your movement, these Icebreaker leggings are designed for high-intensity, cold-weather activities. They’re made with a ZoneKnit body-mapping technology that retains warmth and breathability where you need them most. They’re also finished with sleek flat lock stitching, which means this pair is virtually chafe-free.
Material: Merino.
Colors Available: 2.
Best Sustainable Thermal Underwear
Nike Pro Dri-FIT Tights
Introducing the go-everywhere, do-everything insulation layer for chilly legs. Not only are they extremely versatile—you can wear them skiing, wear them under a suit, wear them wherever—but they’re made from recycled polyester, as part of Nike’s “Move to Zero” journey toward zero carbon emissions and zero waste.
Material: Recycled polyester.
Colors Available: 4.
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