Outdoor Gear
Why a Better Jacket Will Not Keep You Warm and Dry on Its Own
Outdoor Gear Coach's Mike Parsons explains why staying warm and dry depends on how you layer, ventilate and fuel yourself, not on the price of a single garment.
Video from The Outdoors Station.
Generated from the canonical interview transcript and validated against source data by Guests on Air.
Why won't a better jacket keep you warm and dry on its own?
A jacket only works as part of a system. Most waterproofs do not let air through, moisture vapour escapes only when conditions inside are warmer and wetter than outside, and warmth comes from your body and the dry air your layers trap. Choosing layers that fit together, and using them well, matters as much as the fabric itself.
Ask a crowd of strangers online what to wear for a first ascent of Ben Nevis and you will get a hundred confident, conflicting answers. Some of that advice is harmless. Some of it could leave a walker cold, wet and in real trouble on a hill where the weather can turn within an hour.
Mike Parsons has spent 40 years in the outdoor industry, including creating the lightweight OMM brand, and now runs Outdoor Gear Coach with textile historian Mary Rose. In a conversation with The Outdoors Station, he set out why so much received wisdom about outdoor clothing is marketing rather than performance.
His central point is uncomfortable for anyone who has just bought an expensive jacket. The garment does not do the work on its own. Staying warm and dry depends on knowing what fabrics can and cannot do, how layers fit together, and how the body makes the heat that clothing only holds on to.
Key takeaways
- Most waterproof jackets are not air permeable, so sweat escapes as vapour only when it is warmer and more humid inside than out.
- A thin windshield worn more often protects an expensive waterproof and cuts the overheating that leads to condensation.
- Buy layers rather than single garments, each sized so it fits properly over the one beneath it.
- Dry air is the real insulation, and a thick down jacket works best as a top layer when you stop moving.
1. Breathable does not mean air flows through
Mike opens his training with a simple question about breathability. Asked whether a breathable fabric lets air pass through it, most people say yes. In fact, he says, the great majority of waterproof garments are not air permeable at all, and that first surprise changes how people think about the jacket on their back.
Sweat leaves as moisture vapour, not as air. Membranes such as Gore-Tex combine a microporous layer with hydrophilic polyurethane, and vapour moves out only when the temperature, pressure and humidity inside the garment are greater than outside. Mike compares it with water that only flows downhill. When the gradient runs the wrong way, the moisture stays in.
His answer is one most walkers ignore: a plain, thin windshield. Many British walkers pull on a waterproof the moment the wind rises, overheat, and blame the fabric for the condensation that follows. A windshield keeps them drier and saves the waterproof for real rain, which matters more as fluorocarbon water repellent finishes disappear and jackets soil faster.
2. Choose layers, not garments
The three layer system most people learned is, in Mike's view, a marketing message aimed at newcomers: a base layer, a woolly jumper and something over the top. It does not work very well. His colleague Chris Townsend, a long distance hiker and gear tester, wears up to seven layers, each accurately sized so it fits over the one below.
A colleague working in a store in the United States spotted the deeper problem. Customers were selecting a garment rather than a layer, with no thought for what they already owned. Fashion layering makes it worse, because it is designed to show the layers underneath, while performance layering is designed so that wicking and warmth actually work.
Mike's courses, run as continuing professional development for outdoor leaders, teach people to ignore the marketing label and read the truth label inside, which by law lists the polymers used. There are only five key polymers and four categories of textile, each with a distinct function. Simple home tests for windproofing and wicking do the rest.
3. Warmth comes from you and the dry air you trap
Down is often called the best insulation, but Mike reframes the question. What insulates is air, as long as it stays dry. Fleece, knitted base layers and down or synthetic fill are all ways of holding air, in rising amounts. Thick down jackets are fashionable as mid layers, yet worn that way they make people overheat quickly.
Climbers learned the fix years ago. Because climbing is intermittent, you wear just enough to stay comfortable while moving and pull on an over jacket at the belay. Walking is intermittent too, with stops for lunch and drinks. Food matters as well: roughly two thirds of the calories people eat become heat, and clothing only holds on to it.
His conviction comes partly from history. With the Mountain Heritage Trust, Mike and Mary Rose had early Everest clothing recreated and found the silk and wool layers more flexible than modern kit. That research sits behind the book Keeping Dry & Staying Warm (Part 1): How to stay dry, warm or cool in the outdoors. You, the environment, your garments and layering techniques. (part of series of 3), which argues that the garment does not do it all for you.
