Best Thermal Underwear for Winter Travel

Run a hand inside the Thermajane set and you feel its split personality: a fuzzy, fleece-like interior against the skin, and a slick, almost silky face on the outside. That outer face is the useful part. Jeans slide over it instead of catching, dresses hang clean, and nothing bunches behind the knee when you sit down on a train.

Warmth is the other half of the story. It runs warm for a mid-weight knit, and the slim cut means it goes under your usual clothes without pushing you into a bigger pair of trousers. On a cold trip that's the difference between packing one pair of trousers and packing two. It also keeps its shape through repeated washing, which matters when two sets have to cover a week.

The seams are the place to watch over the long run. The crotch and underarm seams show strain before the fabric does — ours came through a season of regular wear without a problem, but if this is your only base layer for a two-week trip, treat the seams as the part you'll be replacing first.

Most men's long johns migrate. The cuffs climb the calf, the shirt escapes the waistband the moment you bend, and by mid-afternoon you're hiking everything back into place. This CL set stays put — the knit is snug without strangling, and pulling on boots, waders, or a work coat leaves everything where you left it.

Warmth lands where we want it for winter travel: enough for outdoor work in genuine cold, not so much that a heated airport terminal turns into a sauna. The stretch in the blend does a lot of that work, and a plain cotton long john feels stiff and clammy by comparison — one reason we steer travelers away from all-cotton sets.

Value is the other reason it's our men's pick. The warmth and construction hold up against sets that cost more, and it covers a ski weekend, a hunting trip, and the walk to the office in February without complaint. The cuffs run snug at the wrist and ankle — a nuisance for the first minute, and the reason nothing rides up after that.

A snowboard run is a decent stress test for a base layer. You work hard on the way down, sit still on the lift, and end up damp inside a shell either way; the set that keeps you comfortable is the one that moves moisture instead of holding it. That's where the romision earns its place, and it's why we point active travelers here rather than to a heavier fleece.

The knit is smooth and stretchy, closer to a compression layer than a loose waffle, so it slides under snow pants and a jersey without a wrinkle, and the long inseam keeps the cuffs down inside boots. A tall collar is a small thing we ended up appreciating on a windy chairlift.

Where it gives ground is thickness. If you want a set for standing around in single digits, this is thinner than that job needs — it's built for movement and the heat that comes with it. For a trip that mixes a ski day with a city afternoon, though, that versatility is worth more than extra loft, and it rinses and dries quickly enough that one set can cover a week.

Packing light and dressing warm pull in opposite directions, and a base layer is usually where the compromise happens. The PISIQI set is the one we keep coming back to for a carry-on: it folds small, adds almost nothing to the bag, and slides under leggings without a visible seam or a wrinkle.

Thin doesn't mean flimsy. The knit is soft with a light fleece back, and it holds heat better than its weight suggests — warm enough for a cold platform at seven in the morning, comfortable under a sweater all day. What we noticed most is the finish: it doesn't cling to outer layers and it doesn't roll at the waist, two things that make a thin set feel cheap. There's a gusset in the bottoms too, which sounds like a small detail until you've climbed four flights of stairs with a backpack on.

It's a layering piece, not a standalone. Wear it alone in a chilly room and you'll feel every draft; the fleece is light and the fabric is deliberately thin. For a trip where you're moving every other day and rinsing things in a sink, that thinness is the whole point.

Not every winter trip needs a premium base layer, and this is the set we point to when the budget decides the purchase. At the bottom of this group's price range, the WEERTI still delivers the part that matters: it's warm, it's soft against the skin, and it layers under snow pants or jeans without a fight.

It's a light, stretchy fleece-back knit, and it does its best work under something else rather than on its own. Beneath a sweater and a coat it takes the edge off a cold day; alone in a chilly room it's thin enough that you'll notice. The waistband stays put, which is not a given at this price.

The material is where the savings show. The knit sits on the thin side of this group, and some of the other sets here arrive feeling denser and smoother in the hand. Treat the WEERTI as the base layer it is — a first set, a spare, or the one you take on a trip that might ruin a good pair — and it does everything you need it to.

Not every winter trip is an arctic expedition. For a week of museums, trains, and wet cobblestones at 40 degrees, a fleece-lined set is overkill, and this waffle knit is what we pack instead: breathable, softly textured, and cool enough to wear indoors without cooking.

The waffle structure is doing real work. It traps air and holds warmth the way a flat knit doesn't, but it also lets heat escape when you start moving, so you're not peeling layers off the moment you step into a warm station. The cotton-and-synthetic blend keeps it from feeling clammy the way a pure cotton set does.

The cut is a genuine plus under jeans and a sweater — slim without restricting, and neat enough at the cuff to sit under a jacket sleeve. Wash it cool and skip the dryer, because a cotton blend this soft has room to shrink.

It's one of the cheapest sets in this group, and it doesn't feel like a compromise: the stitching is tidy, the fabric is soft out of the bag, and it holds its shape through a wash. For a mild-weather trip, that's all the base layer you need.

The MEETYOO set fits like athletic base layers rather than long johns — snug, stretchy, smooth. If you've worn compression gear for running, this is the same idea in a winter weight, and it's why it earned a place here for trips where you're moving rather than standing.

It's non-cotton, so it dries quickly and doesn't hold sweat against your back, and the shirt tucks fully into the pants, which stops the draft at the waistband. It handles well-below-freezing days when you layer properly over it, which is about what a knit this thin can honestly claim.

Where it loses ground to the picks above is warmth standing still. Sit on a cold bench for an hour and you'll feel the difference between this and a fleece-lined set. Keep it for the days you're working and it's excellent; keep it for a week of sightseeing and you'll want more.