Winter can be tough. Some Southerners start to shiver the moment temperatures drop below sixty degrees, while Northerners are out in tank tops and their best shorts when the temp is near freezing. From Alaska to Arizona, though, somebody somewhere is going to be feeling the chill this winter. That’s why having the right gear (like the best thermal underwear) can help tremendously. 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 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 toddies are brewing.
Shop these top picks from some of the best online clothing brands for men, and be grateful that you did as soon as temperatures start to drop drastically. (Also, don’t forget to pair your thermal underwear bottoms with one of the best thermal shirts for maximum warmth!)
Ibex Woolies 2 Bottoms
Merino wool is nature’s miracle fabric. So, it’s the perfect material for everything from beanies and scarves to shoes and thermal underwear. For the latter, we love Ibex’s all-new Men’s Woolies 2 Bottoms. These newly launched thermals boast a 240 gsm that’s ideal as an ultra-toasty baselayer in even the coldest weather. The skin-tight natural feel and covered waistband ensure they don’t ride up and everything stays exactly where you want it.
Smartwool Merino 150 Base Layer 3/4 Bottom
Sometimes you just don’t need a full-length thermal. Smartwool’s brand new Merino 150 Base Layer ¾ Bottom is a three-quarter-length bottom that provides the ultimate versatility. The 150 gsm weight works well as a lightweight base layer for fall or layered up for chillier winter activities. Either way, it offers everything we love about Merino wool, including odor resistance, moisture-wicking, and the ultimate in temperature regulation.
Aether Vapor Base Layer Pant
Aether’s catalog runs deep with design-focused active urban apparel, and that includes even the lowly thermal underwear. The Vapor Base Layer Pant is crafted from a synthetic-blend stretch jersey fabric, so it offers all the benefits of high-quality synthetics: It’s insulating, quick-drying, and odor-resistant. But, it’s a lot softer and more naturally comfortable than most lesser synthetics. All of which makes it ideal for everything from high-intensity workouts to extreme outdoor adventures.
Beyond Clothing Celeris Midweight L2 Long John
We’ve long been fans of Beyond’s highly technical outdoor apparel. The Celeris Midweight L2 Long John is the perfect base layer for mid-winter activities. As part of the company’s L2 (layer 2) layering system, they’re slightly heavier than most next-to-skin base layers, with extra heat retention and breathability. We love them for snowmobiling, backcountry skiing, winter hikes, and the like.
Icebreaker Merino 200 Oasis Bottoms
Crafted from 100% Merino wool jersey fabric, Icebreaker Merino’s 200 Oasis Bottoms are well-suited for all manner of snowsports. With a slim fit and gusseted construction, they’re designed to sit next to your skin and move freely with you. Flatlock seams and a brushed elastic waistband ensure an ultra-comfortable fit without chafing.
REI Co-Op Midweight Base Layer
For cold mornings at your cabin or chilly mornings on the slopes or the trail, the right long underwear is going to prove mighty useful, mighty warming, and mighty essential. REI’s version keeps you warm without slowing you down.
Odlo Blackcomb Base Layer Bottoms
Odlo has a knack for turning innovative fabrics into underrated and yet highly useful basics, like these performance-ready bottoms, featuring anti-odor technology and ventilation for all-day utility.
Duluth Trading Go Buck Naked Performance Base Layer Pattern Pants
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.
Mack Weldon WarmKnit Long Underwear
A micro-waffle knit gives some classic texture to another pair of thermals that were 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
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.
Lululemon Surge Cold Terrain Tights
Lululemon uses its own proprietary 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, with a close fit that’s ideal for running. Take a look at some of our favorite workout clothing brands for more options.
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