Review: The North Face Jammu

Generally, the better a jacket is at keeping the wet out, the better it is at keeping the wet in. While the wind whips and the rain pelts, you stay dry ... until your body temperature climbs and that muggy, wrapped-in-plastic feeling sets in.

Waterproof-yet-breathable fabric technologies are abundant in the outerwear world, but even with rain jackets marketed as "ultra-breathable" (as most are) some condensation still builds up inside the shell, leaving you clammy, wet, and wondering why you wore a jacket in the first place.

With its new Jammu jacket, The North Face is the latest manufacturer to tackle this elusive unicorn of a truly breathable, truly weatherproof piece of outerwear. The special sauce inside the Jammu is Polartec's NeoShell membrane, which claims to possess the industry's highest levels of clam-free waterproofing.

The Jammu is an expensive jacket ($400), but the price is made less painful by a handsome look and a smart design. The cut is just generous to allow for light layering underneath, while the soft shell fabric provides enough stretch to keep you from feeling claustrophobic. Pockets placed high on the body allow easy access when wearing a pack harness, and the helmet-compatible hood adjusts to fit anybody's dome. It seems best suited to hiking, camping, skiing or snowboarding in above-freezing conditions.

The outer layer is complemented by a soft fleece inner lining that gives the jacket a warm, cozy feel. Sandwiched between the two is Polartec's NeoShell fabric. Thin, waterproof, and super air-permeable, Polartec claims the NeoShell membrane pulls sweat vapor out of the jacket at an extremely low pressure. The result? Heat and moisture supposedly get vented before you get a chance to feel it.

Even though every foul-weather jacket on the market claims to be the most breathable ever, the fact is, it's pretty hard to test how much moisture a jacket retains when you're out in the field. Many of the "most breathable jackets in the world" feel very much the same, and most of my tests end with a limp "meh."

On a testing day that began with rain that turned into snow and ended with an inexplicably hot sun, the Jammu eliminated "meh" from my lexicon.

The outer shell is remarkably tough, especially given how soft it is. Rain beaded up and rolled off, and snow brushed off without soaking. Foliage couldn't scuff it; I waded through shoulder-high brush several times, but the tough polyester exterior looked as good as new by the end of the day.

And, as it turns out, the Polartech NeoShell layer is the secret to the Jammu's success. I built up a decent amount of heat chugging uphill with a 30-pound pack, but the jacket never felt overly hot. The sun eventually poked its head out, but I didn't want to take off my pack to strip off the Jammu, so I just opened up the pit zips and kept going. I never felt anywhere near clammy.

On a sunny, windy day hike in Lake Havasu, the Jammu repelled 20-plus mile-per-hour gusts all day. But despite the afternoon sun, I never overheated. I was even able to run the last mile down the trail without feeling like I was wearing a sauna suit.

WIRED Breathes amazingly well. Blocks rain like a hard shell. Excellent fit. Fuzzy lining adds warmth and soft touch. Performs well in a multitude of conditions.

TIRED Costs more than a PlayStation 3. No media cord ports. At 1 pound, 10 ounces, it may be too heavy for ultralight backpackers.

Photos: Ariel Zambelich/Wired.com