Best base layers 2019: for skiing, running, hiking and stargazing this winter

How to keep warm in winter? That’s easy – get layering. Whether you’re going running, hiking, skiing, or planning to spend a bit of time outdoors in the Arctic Circle looking for the northern lights, what you wear against your skin makes all the difference. 

A base layer is the layer you wear first before you put on anything else and one that keeps you warm and soaks up your sweat. It traps hot air next to your skin, but a good base layer should also be breathable enough to wick (remove) sweat from your skin. After all, you can’t be wet while simultaneously trying to keep warm. 

Cue a bunch of natural and synthetic fibres that claim all kinds of properties. However, finding the best base layer for you need not be complicated. 

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How to buy the best base layer for you

There’s basically a choice between merino wool (from Australia and New Zealand’s merino sheep) and synthetic fibres. Merino wool retains heat, it’s breathable so allows sweat to escape, and as a bonus, it’s naturally antibacterial so can be worn for days on end without needing to be washed. 

The other choice is a synthetic base layer, which use various polyester blends that are also breathable, but perhaps not quite as warm as merino. In practice, many base layers use a mix of merino and synthetics.

One thing to remember when looking for the best base layer for you is design-led ventilation. Although you’re preparing for the cold, if you’re likely to sweat (i.e. you’re exercising), it’s very likely that even the finest merino wool won’t be able to wick away everything. So look for a base layer that can be unzipped at the front to allow you to cool down quickly with a burst of cold air.

Here's our guide to buying the right base layer no matter what activity you're undertaking.

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There was a time when Icebreaker’s merino wool base layers were super-expensive and peerless in their ability to wick away sweat and yet stay sweet-smelling for days. With the proliferation of merino wool, that’s no longer true, and Icebreaker has now pivoted to also being one of the best value brands around.

The slim fit 175 Everyday Crewe is something of an all-rounder. A long-sleeve base layer, it’s warm and wicks away sweat well, doesn’t smell, and dries in hours. So as well as being a base layer in winter, it can also be at the core of a capsule wardrobe for travel in warmer climes.   

Why bother with merino wool when you can have yak wool? Using hair from the long-haired bovid from the Himalayas, Kora claims that yak wool is 40 percent warmer than a Merino equivalent. That’s hard to test, but this is definitely a base layer to consider is you’re venturing into sub-zero temperatures. 

A tight-fitting and very soft base layer, the Shola 230 Zip for men and women has, as its name suggests, a quarter zip that not only gives you excellent emergency ventilation, but snugly fits around the neck. 

If you want something eco-friendly, always consider Patagonia. On this, its top-of-the-range advanced base layer, 51% New Zealand merino wool is blended with 49% recycled polyester – Capilene – to create a fabric that’s both breathable and warm. 

Available in black, blue and teak – and looking much more like a regular pullover than a base layer – the Capilene Air is a great all-rounder for the outdoors, able to insulate, dry quickly and be odour-free for days. Like most good base layers it’s figure-hugging, but uses a clever seamless construction so there’s no chafing. It’s also got soft elasticated sleeves that are easy to roll-up. 

Here’s a product that demonstrates the advantages of combining the properties of merino wool and ‘technical’ fibres (read: polyester). A two-layer construction with flatlock seams, the Lifa Merino 1/2 Zip has 100% merino wool on the outside and a layer of Lifa synthetic polypropylene fabric against the skin. 

It’s thus really warm, so ideal for skiing, but when you get down the mountain into warmer temperatures – and you’ve got a sweat on – its wicking properties are boosted by that 1/2 zip for easy and quick do-it-yourself ventilation.  

Fashioned from a fabric called Phasic AR, this midweight base layer with a crew neck design is 100% polyester. It’s warm, it’s figure-hugging, it wicks away sweat well and it’s really hard-wearing. Using 100% polyester does have its drawbacks; unlike merino wool blends, this anatomically shaped base layer does smell after a few wears. 

It’s also not as soft as some fabrics. However, those drawbacks will be cancelled out for many because of the Arc'teryx Phase AR Crew’s durability; this is a base layer that should last for years.  

Few base layers feature 100% merino wool, and those that do like to tout their lightweight features. Not so the Smartwool Merino 250 Baselayer Pattern Crew, which sticks to all merino, but uses a much heavier knit than most. Consequently, it’s very warm and very good at wicking sweat away. A crew neck design with set-in sleeves, it’s also got flatlock seams to minimise chafing. 

Since it’s heavier than most merino wool base layers, it’s probably not the ideal choice if you’re out on a multi-day hike because it will take longer to dry after a sweaty day in the mountains. 

The trouble with base layers is they’re only one part of the layering system that’s so important when out in the cold. The next garments you need to think about, of course, is a buff or scarf, and a hat, which close any gaps around your neck. 

Cue the Aclima WarmWool Men's Hooded Sweater from Norway, which includes a clever balaclava hood that can also be worn as a buff. Or you can simply stow it, using a zip for extra ventilation. Fashioned from an extra-soft 100% merino wool, this base layer is longer than most, too, so easy to tuck-in to trousers. That’s crucial for skiing and climbing.  

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