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The Best Thermal Underwear for Braving the Cold Weather Ahead

Winter can be tough all around. Southerners start to shiver the moment temperatures drop below fifty degrees, while Northerners are out in tank tops and shorts when the mercury shows its nearly freezing. From Alaska to Arizona, though, somebody somewhere is going to be feeling the chill. Luckily, thermal underwear is here to save the day, with some styles featuring the latest in fiber tech to help keep us warm, whether for a day on the slopes, or for a snowy commute. Call ‘em Long Johns, thermals, flannels, or tights; they all offer a sleek extra layer under pants or jeans, but many also work with shorts to help keep muscles warm for a morning run or workout. They can even look kinda sexy when worn on their own, for those cold winter nights around the house when the fireplace is roaring and the hot toddys are brewing. 

2(x)ist Cotton Long Underwear

2(x)ist Cotton Long Underwear

Made from a super comfortable 100% cotton knit, these undies are built for performance, and score some serious style points, too. The buffalo plaid pattern makes them the perfect pair to pull on for a lazy Saturday morning at home, but you’ll feel toasty wearing these under a pair of jeans or khakis the rest of the week. 

Uniqlo Heattech Ultra Warm Long Johns

Uniqlo Heattech Ultra Warm Long Johns

The designers at Uniqlo clearly got an “A” in fabric science; bringing bio-warming technology to long underwear that makes them so warm you’ll want to wear them all winter long. The fabric is constructed to absorb water vapor from your body (OK … that’s pretty much sweat) holding it in miniature mesh pockets, then converting that moisture into heat. That’s a lot of work for a pair of underwear! 

Duluth Trading Buck Naked Base Layer

Duluth Trading Buck Naked Base Layer

Duluth Trading is known for creating premium clothes for guys who really work for a living. Grab this pair of long johns design-tested by construction workers, and enjoy their “no-pinch, no-stink, no-sweat comfort.” The camouflage pattern is a classic that will look just as great with a pair of shorts as it will with carpenter pants and work boots. Their low-profile seams promise no chafing, and the elastic waistband is even brushed on the inside to be soft next to your skin. 

Jockey Thermocore Pant

Jockey Thermocore Pant

Leave it to Jockey to improve on its own classic. The lightweight Thermocore fabric blend provides warmth, wicking, and comfort — all with an anti-microbial finish. They’ll keep you feeling fresh and odor-free; all while keeping you warm and dry. We particularly like this Forest Heather green, but grab the style in Black, Midnight Heather, or Lava Heather, too. 

Mack Weldon WarmKnit Long Underwear

Mack Weldon WarmKnit Long Underwear

A micro-waffle knit gives some classic texture to another pair of thermals that was designed as much in the lab as in the pattern-making room. Mack Weldon blends super-soft Modal with super-warm Thermolite polyester; then throws in natural wool and spandex for comfort. Like all Mack Weldon products, they’re designed to be as elegant as they are functional. 

Patagonia Capilene Midweight Bottoms

Patagonia Capilene Midweight Bottoms

Doing the right thing to keep you warm and to save the planet, Patagonia uses 100% recycled material to create Capilene bottoms that also feature HeiQ Fresh durable odor control. Capilene is Patagonia’s own wicking and fast-drying base layer fabric. HeiQ is its durable odor control technology. The bottoms have a nice smooth face, so they’re comfortable, but also make it easy to pull on that next layer … or layers, depending on just how big of a winter adventure you have planned for today. 

Icebreaker Oasis Merino Wool Jersey Leggings

Icebreaker Oasis Merino Wool Jersey Leggings

Like a sweater for your legs, these leggings feature nature’s warming, wicking material; 100% merino wool. Hey, how do you think those merino sheep keep so warm? The yarn has a built-in ability to resist odor and is naturally renewable, recyclable, and biodegradable.The design itself is sleek and modern, featuring flat-lock seams to prevent chafing, and a gusset for improved fit and added comfort. 

Lululemon Keep the Heat Thermal Tight

Lululemon Keep the Heat Thermal Tight

Lululemon uses SenseKnit technology for these tights that look like they’ve come back from the future just to keep you toasty and dry. They’re designed to regulate your inner temperature, and the ribbed texture provides added support over major muscle groups. These are definitely the pair to throw on when your favorite recreational winter sport turns into an outdoor workout … even if that just means fighting your way through a snowstorm to get to yoga. 

Smartwool Intraknit Merino 200 Bottom

Another entry in the merino wool category, this pair is crafted with a poly/stretch blend and Smartwool’s own 3D knit, making for a better fit and improved movement. Sport Yarn means this pair dries more quickly, keeping you fresh throughout the day; also offering odor-resistance and durability. Smartwool even includes “gender-specific” mesh ventilation zones to keep you dry and comfortable. 

L.L. Bean Two-Layer Union Suit

L.L. Bean Two-Layer Union Suit

Finally, there’s the grandpappy of them all; L.L. Bean’s classic union suit. The fabric is an unbeatably warm and comfortable cotton, wool, and nylon blend knit into a soft, double-layer construction that adds warmth and flexibility. It’s the ultimate lumberjack statement piece, looking and feeling toasty when paired with classic jeans and layered under a field jacket … but makes for a pretty sweet onesie when worn all by itself. 

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