The Packable Lightweight Rain Jacket: Essential Trail Gear

Every seasoned traveler will agree the packable lightweight rain jacket is essential gear for the road: it’s a plucky little piece of outerwear, a compact, portable, utilitarian garment that promptly emerges from your pocket or bag to shield you from unanticipated drizzle at the cab stand or the sprinkle that insinuated itself on your Italian cathedral tour.

And so it goes for a day hike where weather at the summit might be vastly different from conditions at the trailhead: the packable lightweight rain jacket is indispensable gear that rises to the occasion so you won’t need to run for cover, even if you must sidestep a few puddles on the path. But they’re not all the same. A closer look suggests key questions to ask when choosing this essential piece of outerwear.

Q. What features are important in a rain jacket?

Several details matter. When you choose a lightweight rain jacket, think about how you’ll wear it:

  • Seam Taping - The jacket is only as waterproof as its seams; look for taping or welding. But seam tape should not be used alone as an indication of watertightness: a water-resistant jacket can have taped seams.
  • Zippers - Look for a rubberized coating or storm flap to keep out water; zippers must also have a “garage” to shield the hole at the end of the zipper track.
  • Hood - If you will actually wear your jacket in the rain, it must have a hood. Design variations include brims, adjustable openings, zip-offs or snap-offs, and stowaways.
  • Pockets - More pockets translate to more storage: some rain jackets are so generously outfitted with pockets you might even decide to forego a pack for a brief outing. Choose a style with an interior pocket to protect delicate electronics or a smartphone. And some rain jackets are made to pack down inside their own pocket, so the entire bundle can be dropped conveniently inside a pack or bag.
  • Vents - Rain jacket designs sometimes include mesh liners in torso pockets, or “pit zips” for additional ventilation in the heat: venting improves a rain jacket’s breathability.
  • Adjustability - A drawstring in the hem can cinch a rain jacket closed for additional protection, likewise the drawstring in its hood and adjustable closures at the wrists. A longer jacket may also have a drawstring at the waist to further customize its fit.
  • Fit - Size your jacket according to your activities. If you plan to wear it while cycling, for example, make sure it’s comfortable when you lean forward to reach for the handlebars, that the cuffs don’t ride up, and the shoulders are not too snug. If you anticipate you’ll wear layers underneath, size your jacket for a looser fit. And while a snug fit tends to maximize breathability, a loose fit provides more ventilation.
  • Packability - A rain jacket’s weight will be the biggest determining factor of its packability. But even a very lightweight jacket can still possess the same or similar functionality as a heavier one. The Outdoor Research Helium II is an example of an ultralight jacket that offers superior protection, but packs down to the size of a granola bar.

Q. Are all rain jackets waterproof?

No: “waterproof” describes a material’s ability to keep water on the outside. The extent to which it does this occurs along a continuum as indicated by the “column” test, where a one-inch diameter tube placed vertically over a piece of material is filled with water, and then the water’s height in the tube is recorded in millimeters when the material begins to leak. A fabric that withstands 20,000 millimeters of water, for example, earns a rating of 20K.

But the rating does not tell the whole story of a jacket’s impermeability against the elements—other important benchmarks include the construction of its seams, type of material and its thickness, and other design specs. While all material resists water to some degree, only a truly waterproof jacket will stand up to a squall.

Q. What's the difference between waterproof and water-resistant rain jackets?

A water-resistant rain jacket does exactly what its name implies—it resists water, shedding it in light to modest precipitation. A water-resistant jacket has no waterproof membrane. While it is exceptionally breathable and will protect you from a brief shower, the water-resistant jacket is not completely waterproof in steady or wind-blown rain. Its performance improves when it is treated with a repellent; this encourages water to bead up on the surface of the material and will keep it from seeping in if the treatment remains intact.

If a jacket is waterproof, it is also windproof by default. But it is possible for a jacket to be windproof and only water-resistant.

What is DWR?

DWR, or Durable Water Repellent, is a preparation applied to virtually all face, or outer fabrics in rain jackets; it causes moisture to bead up and roll off the material. This makes a jacket water-repellent, which is not the same as water-resistant or waterproof. The DWR treatment on a jacket is a maintenance item and must be reapplied occasionally (“reproofing”) if you expect it to continue to perform as it did when the jacket was new. And although allowing the DWR treatment to erode will not deplete a jacket’s waterproof qualities, it can affect its breathability. Reproofing your jacket with repellent is a fairly simple process.

Q. How can a rain jacket be waterproof and breathable?

Though this may imply sleight of hand, the terms “waterproof” and “breathable” are not mutually exclusive. We have science to thank for a special, technically advanced waterproof membrane or laminate layer with “pores” so small that water can’t get through from the outside, but vapor can still escape from within—it’s a process known as “moisture vapor transfer,” and it keeps you comfortable when you sweat. “Breathability” simply describes a jacket’s ability to do this.

A waterproof jacket without this impressive layer of material will assuredly keep water out (think old-style yellow rain slicker), but will also soak you to the core after any kind of exertion. Most modern rain jackets possess at least some degree of breathability.

Fast Fact: The first waterproof membrane was Gore-Tex®, pioneered in 1969 by W.L. Gore and Associates, but many other similar materials have emerged in the intervening decades.

Who knew the unassuming rain jacket could possess such a multifaceted personality? Fancy features notwithstanding, make sure your packable rain jacket

Who knew the unassuming rain jacket could possess such a multifaceted personality? Fancy features notwithstanding, make sure your packable rain jacket possesses at least these three:

  • good seam taping,
  • a DWR coating, and
  • a secure hood.

Those will hold you in good stead for most surprise showers. There’s no raining on your parade with a packable lightweight rain jacket at the ready.

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