Which thermal base layer is the warmest?

In the Cimalp range, two product families are rated for intense warmth: the X-WARM, made from synthetic fabric with a double-layer insulating construction, and the WOOL 240, made from thick merino wool. Choose the X-WARM if you sweat a lot, or the WOOL 240 for long breaks and bivvying.

Zip-neck thermal top or crew-neck top?

The zip-neck top (WARM ZIP, X-WARM ZIP, WOOL ZIP) protects your neck when the wind picks up and can be unzipped for ventilation on climbs. The crew neck sits more discreetly under a neck gaiter or jacket collar.

Do you need thermal leggings for winter hiking?

Yes, if you spend long periods standing still or the wind cuts through your trousers. The WARM PANT, WOOL PANT and STRATEGIC PANT are worn under hiking or ski trousers.

Can you wear a merino top for several days?

Yes. Wool helps limit odours, so you can wear a WOOL 200 or WOOL 240 for several days in a mountain hut and wash it less often.

Thermal Base Layers

Cimalp thermal base layers for men and women: tops, zip-neck tops and long johns in CimaWarm® synthetic fabric, CimaWool® merino wool or seamless knit, for winter hiking, skiing and extreme cold.

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Top, zip-neck top or long johns: the pieces that make up a thermal base layer

Stop for a break at the pass, and the wind quickly chills a back soaked on the climb. The first layer, also called a technical base layer, helps prevent this: worn next to the skin, it retains the warmth your body produces and moves sweat to the next layer.

The crew-neck top (TOP styles) fits under a neck gaiter or helmet without adding bulk. The zip-neck top with a high collar (ZIP styles) closes at the neck against the wind and opens up on climbs. For your legs, long johns (PANT styles), also known as thermal tights or leggings, fit under trousers without restricting movement when you bend.

Balanced or intense warmth: match your base layer to your level of effort

A base layer that’s too warm becomes soaked with sweat on the climb, then leaves you cold when you stop. The range runs from lightest to warmest:

WOOL 150, 150 g/m² merino: the lightest option, for sustained effort in cool weather, in any season.
WARM and WOOL 200 (200 g/m² merino): balanced warmth for active winter days.
X-WARM and WOOL 240: intense warmth for extreme cold, wind and long breaks.

The X-WARM TOP 5 H weighs 285 g in size M and has a dual insulating construction; the WARM TOP 5 H weighs 220 g. If you walk fast and stop only briefly, choose balanced warmth. Save the high warmth for ski touring, mountaineering and bivvies.

Synthetic fabric, merino wool or bamboo and silk: which fabric against your skin?

WARM and X-WARM, made from CimaWarm® synthetic fabric, continuously wick away sweat: choose them for outings where you sweat a lot. On WARM, the POLYGIENE® StayFresh treatment lets you wear it longer between washes.

The CimaWool® merino wool in WOOL styles limits odours without any added treatment, so you can keep wearing the same top for several days, from hut to hut. Find all our wool styles in our merino wool thermal base layers.

STRATEGIC styles combine bamboo and silk in a seamless knit, with no raised seams to rub over a long day: an option for sensitive skin. For men, the SEAMLESS TOP has no seams from collar to cuffs and is designed for intense effort during ski touring or winter trail running.

How to wear a thermal base layer under your winter layers

Wear your base layer directly against your skin, in a close fit and your usual size : the fabric stays against your skin, where it absorbs moisture. Over it, a fleece jacket insulates, then a waterproof jacket blocks wind and rain.

Under winter hiking trousers or a ski trousers, add long johns when your legs start to get cold during stops. The fits differ: see our men’s thermal base layers and our women’s thermal base layers.

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