If you already know the key terms and the basic principles of rain jacket technology, this article will help you home in on the jacket that keeps you dry and fits your budget.
On price: with the big brands you pay for the development, the testing and ultimately the performance of the fabrics in the jacket you buy. A top quality rain jacket can cost several hundred euro, so doing your homework first is a smart move.
The key terms
Waterproof versus water resistant
We call a jacket waterproof when it resists enough to keep driving rain out. Brands do not agree on testing standards, but you can trust that any jacket a major brand labels waterproof will handle a serious downpour.
Waterproof and breathable
This type of jacket keeps rain off your skin while moving sweat to the outside. If you are planning an activity where you will sweat hard, this is what you need. Both rain and perspiration can soak the clothing under your jacket, and that is always worth avoiding.
Water repellent
This is a jacket that handles light rain for a short while. Windproofs and featherweight jackets often have a water repellent coating. If the rain keeps coming, this kind of clothing is not up to the job.
Waterproof and non breathable
Think of an emergency poncho. If you simply need to keep the rain off while sitting or standing, this does the job fine and costs relatively little. But the moment you exert yourself, the jacket gets wet on the inside too. And it does not take much wind to render a poncho largely useless.
Windproof
Every waterproof jacket is also windproof. That follows: a barrier designed to stop driving rain also stops the wind driving it. There are also jackets with windproof technology, usually a laminate, that only count as water resistant.
Wind resistant
Essentially the same as a water resistant jacket, but often an ultralight garment that packs into a small pouch. Made for short trips and optimistic forecasts, not for a full storm.
Three in one jackets
A step beyond a rain jacket: this design combines a shell with a fleece inside. That inner layer usually zips into the shell, so you can wear both parts separately as well.
Types of shell
Although the word shell is often used interchangeably with jacket, it can also refer to trousers, parkas and ponchos. It says more about the fabric composition than about the style of garment. Knowing these types helps you choose.
Hardshell
This is another term for waterproof, breathable clothing. The materials in most hardshells are stiffer than in softshells, though more supple versions keep appearing. Hardshells are not insulated, so your warmth comes from the base layer and mid layer underneath.
Softshell
The classic version combines an insulating layer with a water resistant shell. The idea is that a single garment serves as both mid layer and outer layer. The difference from a hardshell is more breathability in exchange for less protection against rain and wind. As designs keep evolving, the category has become a little blurred. Many softshells are also very flexible, which is rarer in a hardshell.
Hybrid shell
This term covers several constructions. In a softshell and hardshell combination, the more waterproof and windproof fabrics sit on the front and top, while the more breathable, flexible fabrics sit on the sides, the back and under the arms. You also find traditional softshells or hardshells with a tougher fabric in high wear areas.
Insulated shell
Usually filled with down or synthetic insulation to hold warmth in winter. If the jacket uses a waterproof, breathable fabric you get a higher level of protection. The seams do have to be sealed for it to count as fully waterproof.
What is breathability?
The breathability of a waterproof, breathable rain jacket is the deal breaker. Nobody wants to walk around in a wearable sauna. The key to avoiding that is moisture vapour transfer.
Sweat vapour leaves your outer layer partly because the warm, humid air inside is drawn towards the colder, drier air outside. How efficiently that happens helps determine how dry or clammy you feel, and improving that efficiency has been the focus of outdoor brands for decades.
You hear all sorts of competing performance claims, which mainly means the familiar names are no longer your only guarantee of a dry walk in the rain.
Today's jackets do breathe far better than their predecessors, although there is no universal test standard or independent certification body measuring that performance.
Some brands work with a low level of air permeability, the scientific term for classic breathability. They use different terminology for it, but generally claim breathability is better or faster. The downside is that direct air exchange also lets warm air out. These jackets therefore need a warmer insulating layer than a traditional waterproof, breathable shell.
Waterproof, breathable technology
The most important part of your rain jacket's fabric is a coating or membrane that blocks rain while letting sweat vapour escape. Because such a membrane is relatively fragile, it is bonded to a protective fabric to form a laminate. Almost every rain jacket is built with a laminate or a coating, and the exact materials vary widely.
Durable water repellent, the DWR finish
Most outerwear, including every waterproof and breathable rain jacket, has a durable water repellent finish, or DWR. If the outer fabric is water repellent, rain literally beads up and rolls off.
Maintaining that DWR finish is often forgotten after purchase, but it is crucial if you want your jacket to keep doing its job. When the DWR wears off, the outer fabric wets out. The membrane underneath still keeps water out, but the saturated face fabric slows the escape of sweat vapour. The clammy lining can even stick to your skin, making it feel as though the jacket is leaking.
The more environmentally friendly DWR finishes used today wear off faster than older products. Reapplying a DWR treatment regularly is therefore part of maintaining your rain jacket. As soon as rain stops beading, or a wet surface starts giving you cold spots, it is time for a fresh treatment.
The layers of a rain jacket
For protection, the membrane or coating of a rain jacket is sandwiched between extra layers. An outer layer resists abrasion and sheds rain, while an inner layer protects against body oils and wear from the inside.
There are three constructions: two layer, two and a half layer and three layer.
The quietest
The membrane or coating is applied to an outer fabric and forms a single piece with it. Inside hangs a loose lining that protects the membrane. Because this construction is quieter, it rustles less as you walk, it is preferred for rain jackets used in town and while travelling. You generally find this design in mid priced jackets.
The lightest
Here the word lightest can be confusing. As with the other constructions, a light but durable outer fabric forms the first layer. The second layer is a polyurethane laminate or coating applied inside it. Finally a protective print goes over that, which is the half layer.
These designs usually do not match the breathability or durability of other jackets, but they are lighter and more affordable. Some wearers find them clammy. A jacket with a dry touch print, which stops the fabric clinging to your skin, makes the difference there.
The toughest
No coatings are used here, only a membrane sandwiched tightly between a sturdy face fabric and a lining. Three layer jackets are generally the most durable and most breathable, and are used for the harshest conditions. They also cost more.
Because such a construction requires many seams, a genuine rain jacket needs fully taped seams to be waterproof. Every waterproof jacket is made that way, so it is not something you need to check separately when buying.
Do not assume a jacket is fully waterproof simply because there is seam tape in the hood and shoulders. That is common practice on jackets that are only water resistant. Equally, the absence of seam tape on a softshell does not indicate poor quality: it is simply not used there, because it adds complexity the intended use does not require.
What else to look at
Zips
From the front opening to the pockets and the pit zips, most jackets are full of zips. To stop water seeping through them you need a rubber coating or a storm flap. Coated zips, also called laminated zips, run a little stiffer. They also need a garage to shield the small opening at the end of the zip track. Zips add noticeable weight, so you will find few of them on ultralight rain jackets.
The hood
Most hoods have a brim and adjustments at the sides and back to fine tune the opening. Jackets without those adjustments are meant for everyday use. The hood on an outdoor brand jacket is usually big enough to fit over a climbing helmet.
Vents
Because even the most breathable rain jacket can be overwhelmed under hard effort, almost every outdoor jacket has pit zips. Some go further and use mesh lined chest pockets that double as extra vents.
Adjustments
Besides the hood adjustments, jackets often have a drawcord at the hem, and longer models sometimes one at the waist too. Most technical rain jackets have adjustable cuffs. With all of those you can close the jacket up tightly so rain, wind and cold cannot creep in. You can also loosen them to improve ventilation.
Pockets
Pockets push up the price of a jacket, certainly when they are waterproof. Some jackets have so many you could almost forget your rucksack. Others place the hand pockets above the hip belt of your pack, so you can still reach them while wearing it.
Packability
An ultralight, thin fabric always makes a jacket easier to pack. Some jackets go further and have a pocket that doubles as a stuff sack. If a jacket has that feature or its own stuff sack, it is described as packable.
Personally I always roll my jacket towards the hood and then fold the hood over the roll. It works perfectly and fits far more easily into your pack.
Two notes from the field
Over the years we have tested a lot of jackets on treks through valleys and climbs in the mountains. Different places and situations call for different materials. A two layer rain jacket can tear while mountaineering, and a three layer one is better there because it is tougher. In our own cupboard hangs a whole range of jackets, depending on the activity.
Carry a heavy pack in the rain for hours and leaks can appear where the shoulder straps sit. We had that problem even with a couple of certified jackets: the pressure and friction push water droplets through the breathable fabric, and eventually your T shirt gets wet. We are not big fans of ponchos, but if you are walking in a very wet region, a large poncho that also covers your pack can be useful. It will not hold up against strong wind and driving rain, though.