Technical rain gear is your backcountry suit of armor: No matter how rainy, snowy, sleety, or windy it gets outside, the right waterproof jacket (and pants and footwear, too, in the worst weather) will keep you dry. A lightweight rain jacket should be in your pack for any hike, for easy insurance. For any high-stakes activity, however, from winter excursions to multi-day treks to high-altitude missions, the right rain gear is downright essential. In the backcountry, wet clothes and wet boots can be uncomfortable at best and dangerous at worst. 

Technical rain jackets (also called shells) are the ones suitable for just those types of trips—think hiking, backpacking, mountaineering, skiing, and climbing. There are scores of them on the market, using an alphabet soup of various technologies designed to be both waterproof and breathable. What they all aim to do: keep precipitation out while still allowing sweat vapor to escape, preventing you from getting wet from the inside. But what works for a 14er bid isn’t necessarily the best bet for hiking the Appalachian Trail. Here’s how to sort through the options.

In this article, you’ll learn:

• The technology behind different waterproof/breathable membranes
• The difference between 2-, 2.5-, and 3-layer jackets
• How to evaluate face fabrics for strength, stretch, and eco-friendliness 
• What waterproof ratings mean
• How to compare different features
• How to keep your feet dry

How Membranes Keep You Dry

There are several ways to add water resistance or waterproofness to a shell, but when it comes to technical gear, the best choice is a waterproof/breathable membrane. These delicate, ultrathin films contain countless minuscule pores—too small to allow water to pass through, but large enough to let body heat escape. That’s important because you can keep the rain out but still get wet from sweat on the inside, and that will make you cold. These waterproof/breathable membranes are bonded to a face fabric (the outside of the jacket) for protection and durability, forming a layered material called a laminate. There are quite a few different membranes out there. 

The oldest and most recognizable is Gore-Tex, made from expanded polytetrafluoroethylene (ePTFE) and polyurethane that lets water vapor from sweat diffuse through. Other brands offer air-permeable membranes, which allow air (but not water) to pass through from both the outside and inside, which is meant to increase breathability (NeoShell, eVent, The North Face’s Futurelight, Outdoor Research’s AscentShell). Yet another choice is a polyurethane (PU) membrane, which is hydrophilic (water loving) and therefore pulls moisture away from your skin. And two technologies—Columbia’s OutDry and Gore-Tex’s Shakedry—dispense with the face fabric and place the membrane itself on the outside of the jacket.  

So which one is best? It depends: Any reputable waterproof/breathable membrane will keep water out. Breathability is the big X factor, and it depends a lot on other design choices in a particular garment, such as face fabric, fit, and pocket placement. And don’t forget: The one membrane that can completely keep up with body heat production at peak exertion has yet to be invented—in the worst conditions, if you’re working hard you might feel swampy in even the most breathable fabrics available. In that case, your best bet is to slow down—moderate your effort to reduce sweating. 

Why Layers Matter

When you’re reading the fine print on a rain shell, you’ll see a stat that reports the jacket’s number of layers. One of them is always the face fabric, and one is the membrane; where jackets differ is on the interior layer. Here’s what the three choices mean.

2-layer 

This construction has a face fabric and a membrane, plus a mesh liner to protect the membrane. It’s the most affordable option, but typically not used in technical shells. 

3-layer

This option pairs the face fabric and membrane to an interior liner, which shields the membrane from abrasion and skin oils. Three-layer jackets are the most durable and often the most breathable—and the most expensive.

2.5-layer

This “in-between” construction has a face fabric, membrane (or coating), and a raised pattern (the “half-layer”) on the interior to protect the membrane. These fabrics tend to be lightweight, but they’re less durable and often less breathable than 3-layer membranes.

Consider the Face Fabric

Membranes are important, but a shell’s face fabric matters, too. It’s the jacket’s first line of defense against the elements, plus any trees or rocks you might scrape—and it also helps determine breathability and comfort. You might see the face fabric’s denier advertised. This is a measure of the density of a material’s fibers, and therefore, its strength. A lower denier (say, 20D) will be lighter and often more breathable, but more delicate; a higher denier (like 70D) will be burlier, but heavier and perhaps less breathable. 

Another important factor: stretch. Generally, stretchy garments are more comfortable to wear because they move with you (particularly important for climbing or scrambling). Some face fabrics have four-way or two-way stretch, allowing for more freedom of movement; others don’t have much give. 

The face fabric is also treated with a durable water repellent (DWR), which helps water bead up on the surface. Traditionally, brands have used PFC-based DWR treatments, but these toxic chemicals have been shown to wash out over time and build up in the environment. Brands are now working on eco-friendlier formulas, and some jackets offer PFC-free DWR. Though greener, these DWRs typically don’t last as long as their PFC counterparts, so you might have to re-treat the shell to restore its highest waterproofing.

What About Waterproof Ratings?

Another technical stat that shell brands like to tout is a measure of the fabric’s waterproofness as determined by a lab-administered water column test. A tube is placed over a swatch of fabric; the stat measures how many millimeters of water (and therefore, pressure) can be poured into the tube before the material starts leaking. A rating of 3,000 to 5,000 mm is considered waterproof against regular rain, but highly technical shells usually rate between 10,000 and 20,000. Because it would take exceptionally high winds to get any rain through a 10,000 mm-rated shell, though, there’s little real-world difference in performance when you get into the higher ratings. 

What Features Do I Need?

Extras—such as pockets, pit zips, and an adjustable hood—make shells more comfortable and functional to wear, but they also tend to make them heavier. Think about your preferred balance of weight and features when comparing options. 

Pockets

First, consider what kind and how many. Hand pockets are great for toting maps and snacks, as well as keeping your hands warm and dry in the rain. Chest pockets conveniently carry phones or GPS units, and internal pockets provide additional useful storage. Also check the size: Will your phone fit in that chest pocket? Do you need pockets large enough to fit climbing skins when skiing? Finally, look at pocket placement: Will you still be able to access the hand pockets when you’re wearing a backpack hip belt or climbing harness? 

Hood

Some hoods are more protective than others. Hoods that have adjustable toggles around the back of the head and/or around the face can be cinched down against nasty weather when necessary; the more adjustment points, the more control you’ll have. Some hoods are sized to fit over a helmet, which is important if you plan to wear it for climbing, skiing, or cycling. Also look at the brim: Some hoods sport substantial brims with bendable wire, which are great at keeping drips out of your eyes. 

Pit Zips & Mesh

Zipped vents under the arms (occasionally, you’ll also see these on the sides or back of a shell) open quickly and efficiently to dump body heat. Some shells also feature mesh-backed pockets you can open for extra venting, but keep in mind that you’ll risk losing anything stored inside them. 

Adjustable Cuffs & Hem

Cuffs that can be tightened with a Velcro tab let you firmly seal out wind and drips, and can be fine-tuned to fit over gloves. A cinchable hem also keeps cold drafts out when necessary, but loosens up for more airflow. 

Protecting Your Feet

Even the greatest raingear in the world won’t do you much good if you forget to protect your feet. And wet feet can be trip ruiners, causing everything from blisters to cold injuries. Fortunately, plenty of technical hiking shoes feature waterproof/breathable membranes. They use the same technologies used in shells, just sandwiched in between shoe layers to provide a moisture barrier for your feet. Some shoes and boots use name brands like Gore-Tex or eVent, while others have a proprietary membrane. 

Do I Really Need Waterproof Footwear?

Maybe. It depends entirely on the conditions you expect. Fully waterproof shoes or boots will protect your feet from water on the outside, but just as with shells, they’re less breathable than their non-waterproof counterparts, and warmer, too. 

This tradeoff is worth it anytime you’re likely to encounter significant moisture: in rainy weather, when there’s heavy dew, on muddy or snowy trails, and trips that require a lot of stream crossings. Keep in mind that higher-top boots offer more protection than low-tops, as water can sneak in via the top of the shoes. 

But if you typically hike in warmer, drier environments, it’s probably better to choose footwear without a waterproof/breathable membrane. You won’t need the extra protection, and the membrane will just make your feet sweaty. 

It’s worth mentioning that many shoes have some level of water resistance, if not complete waterproofness. Materials like leather and nubuck provide some protection naturally, and many models come treated with DWR as well. 

The Extra Mile: Gaiters

When moisture is sure to be a part of your trip—rain-packed forecasts, for example, or any time you’ll be traveling in snow—a pair of gaiters is an excellent idea. These flexible, waterproof fabric shields fit snugly over the tops of your shoes to keep water out. Ankle- or mid-calf-height gaiters work well in wet environments; you’ll want knee-high versions for deep snow. 

To wear them most effectively, make sure to adjust the underfoot straps tightly so the gaiters fit closely to your shoes or boots. Clip the lace hook to your shoelace as close to your toes as you can stretch it, and cinch the tops snugly around your legs. Always wear gaiters under, not over, rain pants, as this makes it darn near impossible for water to sneak in. 

All articles are for general informational purposes.  Each individual’s needs, preferences, goals and abilities may vary.  Be sure to obtain all appropriate training, expert supervision and/or medical advice before engaging in strenuous or potentially hazardous activity.