To choose the right rain jacket, it's important to consider several aspects. First of all, a rain jacket is both waterproof and windproof, so it protects you effectively from the rain and prevents the wind from causing heat loss. What's more, it's designed to allow perspiration to escape in the form of water vapor, ensuring your comfort.
However, it's advisable not to wear a rain jacket during intense physical effort if it's not raining, as your perspiration will be better evacuated naturally without the jacket. A rain jacket is more appropriate when it's raining or in wet conditions where protection from the rain is required.
It's also important to note that the thermal protection offered by a rain jacket is generally limited. If you're planning to explore cold or windy environments, it's often necessary to wear a fleece or insulating layer in addition to a rain jacket to keep warm.
To sum up, when choosing a rain jacket, make sure it's waterproof and windproof, wicks away perspiration and is suitable for the expected weather conditions. If necessary, add an appropriate thermal layer to ensure your comfort in colder conditions.
What's the difference between waterproof and water-repellent?
It's essential to distinguish between a water-repellent jacket and a waterproof jacket. Water repellency refers to a fabric's ability to allow water to slide off in droplets, preventing it from penetrating and weighing down the fabric. However, this property is limited: a water-repellent fabric will not withstand a prolonged or intense downpour for long, and will eventually let water through. What's more, water-repellent treatment tends to deteriorate with time, washing and rubbing. It is therefore necessary to regularly treat the garment with an appropriate solution to maintain its water repellency.
Waterproofing, on the other hand, refers to the fabric's ability to prevent water penetration. A waterproof fabric may absorb a certain amount of water (unlike a water-repellent fabric), but it will not allow water to reach the inside of the garment. A waterproof jacket is made from a microporous material, whose pores are 20,000 times smaller than a drop of water. This keeps you dry while allowing your skin to breathe. That's the difference with oilskins, which are waterproof but not at all breathable. It should be noted, however, that once the surface of the waterproof fabric is saturated with water, perspiration inside the garment is trapped and cannot escape.
In short, a water-repellent jacket is designed to keep water out, but it's not totally waterproof and won't withstand prolonged downpours. A waterproof jacket , on the other hand, is designed to keep water out, offering better protection against the elements. Make sure you regularly maintain your jacket's water-repellent treatment, and choose a waterproof jacket when you plan to face more intense rain conditions.
The weight of the jacket is a less crucial criterion than that of hiking boots, but it's still worth considering because of the significant differences. Bearing in mind that you can always wear a fleece under a light jacket in cool weather, opting for a light jacket has the advantage of reducing the weight of your rucksack and allows you to hike without excessive sweating when the terrain or temperature becomes more challenging.
As for the hood, whether removable or fixed, it can be stored in the collar of the jacket. It's best to avoid fixed hoods if you're bike touring, as they tend to get caught in the wind. Be sure to check for an adjustment system such as Velcro or a lanyard on the top and sides of the hood. A good fit will allow the hood to follow the movements of your head.
Cuffs are usually adjustable with velcro (for a snug fit) or elastic.
It's important to check the pockets, as they can sometimes cause minor inconveniences. If they're too small, they may be difficult to access when wearing gloves. If they're badly placed, they may be right under the shoulder strap of your backpack, rendering them useless. It's best to consider how you'll be using your jacket. When hiking, it's likely that you'll need to handle a map frequently. So you'll need a pocket high enough to store the map easily and open it without difficulty. You may also need a smaller pocket for your cell phone, to keep it close at hand, as well as an inside pocket for your wallet. Everything else can be stored in your backpack. It is highly recommended that pocket closures be waterproof.
The collar of the jacket is an area to keep an eye on, as it can cause irritation to a fairly sensitive area of skin, and act as a privileged entry point for rainwater. A misplaced snap or an unsuitable cut can quickly become a nuisance. So it's important to pay attention to this when trying them on.
Warmth retention is not an essential criterion for the jackets we're talking about, as they're not designed to offer significant thermal insulation. They are designed to be worn with T-shirts or fleeces of different thicknesses. It's important to bear this in mind when making your choice, and to opt for a sufficiently ample size if you plan to walk in cool weather. It's also worth noting that if you're an occasional cross-country skier or snowshoer, a hiking jacket combined with a fleece is a very appropriate piece of equipment. Avoid wearing cotton or wool under your jacket, as these natural fibers have poor moisture-wicking properties.
It's imperative to avoid hiking with an oilskin or a simple plastic poncho. Jacket breathability is crucial, because there's no point fending off the rain if you end up drenched in perspiration. What's more, when your skin is damp or in contact with wet surfaces, you feel the cold more easily. So it's essential that your garment is breathable, i.e. that it allows the moisture produced by your body, i.e. perspiration, to escape. The microscopic pores in jackets hold back water droplets while allowing the steam released by your body to pass through.
Some jackets feature zippers under the arms, allowing you to ventilate without having to remove the entire jacket or open the main zipper. This feature is particularly useful in hot, humid weather, as it allows you to regulate your body temperature.
Care and maintenance
Whichever model you choose, your hiking jacket should pose no major problems in this respect. Water-repellent fabrics are particularly resistant to soiling, and rarely require a full wash. A simple wipe with a damp cloth is usually all that's required. If the water-repellent effect begins to fade, special sprays are available to reactivate it.
How to understand the label?
Some products indicate their waterproofing and breathability characteristics on their label, while others provide detailed information on their website. Waterproofness is measured in Schmerber (or mm), a unit defined by EN 20811 (ISO 811). When it rains, the pressure exerted by water on the garment can vary from 1,300 to 2,000 Schmerber, in addition to the pressure exerted by the wearer (e.g. at the shoulder straps of the backpack). For short day hikes, 2,000 mm may be sufficient, but for multi-day hikes, a minimum of 10,000 mm is recommended. A jacket is considered perfectly waterproof from 20,000 mm, and garments up to 30,000 mm are intended for extreme use. It's important to note that these measurements also apply to overtrousers and tents.
Waterproofing in Schmerber refers to the fabric itself, not the garment as a whole. In our test on hiking jackets, we chose to check the waterproofness of the complete jacket on a mannequin rather than on a sample of the main fabric, as some jackets showed water infiltration at their zipper or drawstring.
There are two ways of indicating breathability. The MVTR (Moisture Vapour Transmission Rate) value corresponds to the quantity of water (in grams) that evaporates from one square meter of fabric in 24 hours. It is expressed in g/m²/24 h. The higher the figure, the more breathable the jacket. Good breathability starts at 10,000 g/m²/24 h.
RET (resistance, evaporation, transmission) determines a textile's resistance to wicking moisture away from the body, and is expressed in Pa × m²/W. Unlike the MVTR value, a lower RET value indicates better breathability. A RET value below 12 indicates a highly breathable fabric, while a RET value above 20 indicates a fabric with low breathability.