Thermal Clothing For Extreme Cold

Wearing the right layers of thermal clothing in extreme cold situations can be the difference between being comfortably warm or miserably cold. Wear too much insulation and you will overheat, increasing your perspiration, that will rapidly cool your body when your intensity levels drop. Alternatively you may not be wearing enough thermal layers to start with. This can also lead to rapid heat loss unless remedied, forcing your body to shut down its extremities to protect your vital organs.

As you can see, wearing the correct layers of thermal clothing for extreme cold environments should be taken very seriously.


Base layers are the first line of defence against the cold. Worn directly next to the skin, they need to be soft to prevent rubbing sores when carrying equipment, offer thermal resistance to trap heat, and be effective at transporting perspiration away from the body. They are one of the most important layers of thermal clothing for extreme cold environments.

Our Factor 1 Plus base layers are made form super soft polyamide yarn that has lots of in-built stretch, providing a snug fit like a second skin. A water loving chemical called a hydrophilic is impregnated in to the yarn during the dyeing process, actively transporting moisture away from the skin to your outer layers. This keeps you dry and also speeds up the drying process after being washed.


Mid layers are very similar to base layers in that they should be worn close fitting, but they contain more fibres to trap warm air, which is the insulator. They are effectively the work horse in your range of thermal clothing for extreme cold.

Sub Zero Factor 2 Thermal Mid Layers


Our Sub Zero Factor 2 thermal mid layers are heavily brushed on the inside fabric face to produce an inner fleece layer that insulates your body from excess heat loss. Their very strong flat seam construction helps prevent any pressure points occurring when carrying kit.


Once you have your base layer and insulation mid layer sorted then your choice of outer layer is often determined by the elements.

If you are working hard and still feel a little cool then putting on a lightweight down jacket will help to add extra insulation without adding too much weight and bulk.

If you are comfortably warm then you may not even need an outer layer at that point in time but you should keep a close eye on the weather and anticipate changes in conditions. Likewise, if you have to stop or your activity levels decrease then you will need to add further layers to compensate for the reduction in heat generation.

One mistake that even the professionals sometimes make is underestimating the power of wind chill on your bodies temperature. It may look lovely and sunny outside but any wind can rapidly cool the body. Carrying a lightweight windproof that can quickly be thrown over your under layers should mitigate a lot of the wind chill effects.

For further information on wind chill visit the Met Office


It's a myth that you loose most of your body heat through your head, at most it is around 10%. Even though the percentage is a lot lower than most people think, it is a good way to fine tune your bodies temperature. If you start to get a bit warm, remove your fleece hat or balaclava. If you are still warm after a few more minutes of doing this then you know you need to remove a larger layer of clothing.

Sub Zero Factor 3 Fleece Beanie Hat With Ear Guards

This also works the other way around. Add a hat if you start to feel cool. If this doesn't warm you up then you know that a larger item of clothing needs to be worn or that you need to start looking for shelter.

The other reason for covering your head and hands is to help protect your extremities from wind burn and frost bite.


Keeping warm and dry in extreme cold weather needn’t be too much of a problem if you listen to what your body is telling you , are aware of your surroundings, and are wearing the correct kit.

Luckily Sub Zero have over 50 years experience manufacturing thermal clothing for extreme cold conditions, with many polar explorers and mountaineers placing their trust in our products.

1 comment

Hi I can’t decide which thermal is suitable for me IAM going to do Sia job which is outdoor standing, and it’s too cold, plz help me with it, what should I buy factor 1 or Mid layers??

Bilal January 08, 2024

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