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The GO Outdoors Guide To Climbing Jackets

When you are carrying heavy loads, whilst wearing both a harness and helmet you need a jacket that can provide as much waterproof and breathable protection as possible. 

 When climbing, a rucksack or a climbing harness may prevent moisture vapour transmission through the fabric at the points of contact, leading to a build-up of condensation on the inside. 

This can be helped by using a breathable climbing jacket as well as a well-ventilated rucksack, with air vents and mesh in the back system.

Jackets for the mountain are all based around getting the perfect fit and the best performance. 

Designed for wearing hour upon hour in the harshest conditions, a slim waterproof isn’t going to cut it up K2. You need a jacket that not only has all the technical ability to keep you warm and venting , stopping condensation and cold spots, but also a jacket that feels good and comfortable. It should also be adaptable and adjustable. 

Anything that hinders your progress, gets in the way of your harness or stops you in your tracks is deadweight on the mountain. 


Climbing jackets are often sold on their breathability. Extremely breathable sounds ideal, but what’s the catch? 

Breathability comes at a price, literally, and that is the more breathable the jacket, the more expensive it will be. The technology behind breathability is exceptionally clever, and when combined with waterproofing or weather resistance, the right breathable jacket can be as good as a second skin. 

  • Breathability refers to the level or air that is able to permeate a jacket and is measured by how much water vapour can pass through the fabric. This can be described as both internal moisture, or water that is created due to activity and sweat, as well as ambient moisture, such as rain and snow.
  • Breathability is measured in grams of water vapour lost over a day long (24 hour) period.  
  • Abbreviated as 'g' or 'gm', this is then given a rating for its level of breathability. Generally the higher the g or gm, the more breathable the garment is.
  • Breathable garments work best when the air inside is humid and warm, the air outside cold and dry in order to evaporate the excess moisture. When the weather produces warm and humid conditions on the outside of the jacket, transmission rates will be lower and could allow condensation to build up on the inside face.  
  • If the mid and outer layers are not in contact then moisture vapour will come into contact with pockets of cooler air between layers, so promoting condensation on the inside of the outer layer, which is why it’s essential to wear clothing as part of a layered, or moisture managing system
  • A jacket designed for the mountain has a tough job as it walks a fine line between risking overheating, or leaving you with too little protection from the cold.
  • Obviously, your layering system should be in place, so your jacket should be the final piece in keeping you warm.
  • Breathable material such as GORE-Tex, e-Vent and Paramo’s own fabrics can all provide excellent levels of breathability.
  • Breathability should be matched with venting areas for extreme inclines and releasing humid inner jacket moisture and heat.

Climbing Jackets- Waterproofing and Water Repellency

Waterproofing is measured in millimetres called a hydrostatic head which indicates the amount water pressure can a jacket withstand before it leaks. For British standards, over 1500mm is legally ‘waterproof’, however on a standard jacket suitable for use whilst climbing, 2000 to 2500mm is an average hydrostatic head. Waterproofing or Water repellency is created via either: 

Coatings (for water repellency): Fabrics are sprayed with a PU (Polyurethane) coating before being made into a jacket. Waterproofing is sprayed on the inside of the jacket and the seams then sealed. DWR- Water repellency (DWR - Durable Water Repellent) is on the outside to form an impenetrable seal from the elements. 

Membranes (for breathability and water resistance): Membranes can be used to make a garment both breathable and waterproof. Expanded PTFE or Polytetrafluoroethylene is used to make a garment waterproof. GORE-Tex and E-Vent are examples of membranes utilising PTFE membranes. 

Close woven fabrics: (for water repellency): Fabrics woven together closely form a barrier against water and moisture droplets. Known as close knit fibres, these do not need to be coated with an additional layer, so are highly breathable. However, these are classed as water resistant, and not water proof, meaning that although these close knit fibres do not actively repel water, they can keep the bulk of the rain off. 

Fitting a Climbing Jacket

Put the jacket on in store, or check as much information as possible about your jacket online. For fitting, online, see our size guides next to each product and measuere yourself for the best fit.

  1. Lift your arms in a diamond shape, to check if the sleeves are as long as they need to be, and if the arms are articulated. The cuffs shouldn’t flop backwards, but should have the capability to be pushed back if you need to vent heat. If you’re buying online, check the measurements of the chest and body as well as the arms.
  2. How short is it? Many mountain jackets are sold in a shorter length called an 'active fit'. However if you want to use a harness, a longer fitting jacket allows you to get to your gear when your arms are above your head. Even though you need longer lengths, a close fit is essential so your mountain jacket doesn't interfere with your movement.
  3. Check the zips. Are they long enough, and do they run without snagging? Are they protected with a waterproof covering or are they exposed? If they are exposed, are the zips waterproof? (You may need to check the label for this.)
  4. Try on the hood. Is the hood broad enough for a helmet? Can you wear it with a hat and does it obscure your vision? Check for toggles or Velcro areas that can conceal your lips and chin from cold.
  5. Where is the venting? Are there pit zips, mesh areas of zips of the arms of the jacket?
  6. Check the pockets. Do they suit your needs? There’s no point I a set of hand warming pockets too high up for you to comfortably put your hands in if your 5 inches taller than the model the jacket was based on. Stash pocket access is common and is one of the few pockets a mountain jacket has. Because you are likely to be wearing a harness and a rucksack, these are usually placed high up so the pocket can be reached even with your gear on.
  7. Does it feel nice? Check the fabric. Is it stiff or flexible? Will it feel good out in the cold?
  8. How is the collar? Hiigh cut collars are important in mountain jackets because they minimise the amount of cold air that can reach inside the jacket, and prevent drips from overhanging rocks making contact with your skin.
  9. Is it too tight or too heavy? Imagine hauling it off and carrying it around when the sun comes out. If it feels like a deadweight, keep looking.
  10. What is it made of? Mountain jackets ususally incorporate coated membranes to provide both abrasion resistance as well as breathability. Typically man made synthetics are used to offer high levels of protection against rocks, whilst also providing a suitable fabric to enhance moisture management as you produce sweat whilst climbing.
The truth is there isn’t one perfect jacket. Your friend might be comfortable with 1000g of jacket comprising all manner of pockets, reinforced areas and top end breathability and waterproofing, whereas you may feel the fit and comfort from a lighter, less advanced jacket does the job for you.

 Choose the jacket for your own specific needs.

  • Sleeves of mountain jackets should be flexible and easy to roll up.
  • Your hood should be able to be tucked out of the way when not in use.
  • Pit zips are common, and are standard with many jackets but the best solution is a deep chest zip, or a full length zip for venting on the move.
  • They can be open and shut as you walk, and with the correct midlayer beneath, you won’t suffer from cold.