I have Scarpa Phantom Tech, technical mountaineering / winter climbing boots. They are generally great but I'm experiencing a strange phenomenon: my feet get seriously cold when I stop moving, although they're supposed to be warm and cozy. Conditions were not Himalayan, they were more like 25-32F (-5 — 0C)! Worse: when I was testing them in my backyard in spring, I also felt cold while sitting at temperatures of 40F (10C)! Something is completely wrong since the boots are designed for winter climbing, where you might be motionless for prolonged periods of time (for example, while belaying).

When I take them off, the boots are completely wet inside because of perspiration (they're fully waterproof with built-in gaiters and a drysuit-style zip). I suppose the wetness causes me to feel cold. However, the manufacturer states they should be breathable. I was wearing trekking socks with merino wool, not cotton socks.

Am I doing something wrong or is it an expected behaviour?

  • 3
    Are your feet normally colder than others around you? Are the boots too tight, limiting circulation? Have you tried one of the various moisture-wicking socks?
    – Jon Custer
    Nov 16, 2021 at 18:16
  • 2
    Your feet should not be sweating in your boots, so I think that must be the problem. As Jon suggests, look at your sock choice first, then the fit
    – Rory Alsop
    Nov 16, 2021 at 18:48
  • I'm inclined to think them being too tight is the bigger issue than the socks here
    – noah
    Nov 16, 2021 at 22:54
  • 1
    Some people excessively sweat on their feet. You can use antiperspirant there too. Nov 17, 2021 at 3:16
  • @JonCuster: 1. No. 2. Not really too tight but neither too loose. Those are technical mountaineering boots so they should have good fit for control. 3. Yes but will look more into them, maybe do extra research and try different types, thanks!
    – Alexander
    Nov 17, 2021 at 11:15

1 Answer 1


Because the proper mountaineering boots are not designed to keep your feet warm, but to keep your feet dry. It's the role of the socks to keep your feet warm, and the role of the boots to keep your socks dry, so that they could keep you warm.

The insulation of the socks work by providing insulation from the environment, and the best insulation realistically available is air (vacuum would be better, but you'd have to pack yourself in thermos).

The good socks catch a lot of air inside, which insulate you, but that can be sabotaged either by making sock wet (water replace air) or by compressing them, which reduces the amount of air significantly, lowering the insulation properties.

Therefore, you want to have boot at least 1 number larger, to enable you to wear thick socks (or even double thick socks), without compressing them too much. However, too thick socks can cause you to sweat extensively. So you need to find a compromise. Being too warm by cold weather is dangerous: you sweat when you move, and then you get really cold.

Please note, that no existing material can breathe while being wet. The membranes work by transferring humidity from warm and humid environment to the cold and dry. In the rain, no material will breathe.

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