How to Choose a Waterproof Jacket for Trail Running

We will find few garments from which we ask more for less. Waterproofing, breathability and durability with minimum weight and maximum packability. Is this possible? Is there a light jacket that meets all our demands? We are going to analyze in this article what you should demand from a lightweight jacket for aerobic sports.

Rain, fog, wind, cold. Can the lightweight jacket do everything? Photo Salomon / J. Saragossa

Anyone who has practiced mountaineering knows about the variability of weather conditions. We could remember a thousand cases of clear days that end in a storm in the blink of an eye or the changes in temperature between a forest and its adjacent meadow or the unbearable wind on the most exposed hills. This happens in the mountains in general, but in trail running in particular these changes are also extremely rapid when, due to altitude or exposure to the elements, we are forced to follow a route with changes in orientation, link sections over different slopes or cross various trophic levels. We recommend that you read, if you have not done so before, the article on tips for rainy activities so that you take certain precautions into account.

When it comes to trail running, having the right equipment is essential to ensure comfort, safety and performance. We have talked in several articles about how to choose trail shoes, trail running packs, poles and other clothing, but trail running textiles contain very particular characteristics that should be emphasized.

Among the essential elements for trail runners, a jacket stands out as a key garment that offers protection against inclement weather and other terrain challenges. In this article, we will explore the essential characteristics that a trail running jacket should have, focusing especially on waterproofing, breathability, lightness and durability.

The Competing Demands of Trail Running Jackets

We have to talk about the requirements for a jacket for trail running or aerobic activities and we should start with the basic question: why will we need a jacket while we are going fast through the mountains? The obvious answer is that to protect us from the rain and, to a large extent, that is correct. However, on many occasions we must resort to it to protect ourselves from the wind and the cold and, in addition to all this, we demand that it weigh and take up as little space as possible, that it wick away sweat and that it be durable.

BarrabesWill our lightweight waterproof jacket withstand any intensity of rain?

Although they are not special demands, in fact it is what we ask of all outdoor jackets, in the case of trail running this level of demand borders on very demanding levels. We want the most breathable and lightest jacket, but with acceptable levels of impermeability and resistance. Since waterproofing and breathability, as well as lightness and resistance are usually antagonistic, to what extent can such opposite needs be united in a single jacket? Let''s analyze it carefully.

Waterproofing and breathability depend on the technologies and materials used in the garment: a piece of thick, dense plastic will be very waterproof, but not breathable. On the other hand, an airy garment will wick away sweat very effectively but will not stop the rain. Between the two options, membranes were discovered, which allow the evacuation of water vapor from perspiration, but do not allow liquid water from rain to pass through.

In the characteristics of the membrane, there will be the trade-off point of waterproofing and breathability with which we choose our jacket. Unfortunately, the fully waterproof, fully breathable jacket does not yet exist. Until that day arrives, we will have to choose a jacket with characteristics that adapt, as far as possible, to our tastes and needs.

Ramón FerrerIn competitions, do we prefer breathability and lightness or impermeability? Photo Ramón Ferrer

Something similar happens with the characteristics of being lightweight and being durable. A very lightweight material is usually also extremely thin. It is true that there are materials that are resistant due to their internal structure and in others, factors such as the type and thickness of the fabric, the denier or weight of the thread or the added reinforcements are taken into account.

Being lightweight is a basic in an activity in which, if we have chosen the day well, it is most likely that we will not have to take the jacket out of the backpack. The same goes for packability: it is very important that in the small trail running backpacks the space occupied by each of the pieces of our equipment is as small as possible.

Due to their characteristics, the activity of mountain races takes place in a variety of landscapes. It is not negligible, in fact it is usually common, that in the mountains we have to cross forested areas with plants equipped with thorns and branches crossing our path. If we cross these areas at high speed, it is quite likely that, at the very least, we will get a scratch. Therefore, do not choose the thinnest model for areas especially covered with vegetation.


We talk about waterproofing as a crucial feature in a trail running jacket, as runners deal with variable and often unpredictable weather conditions. A waterproof jacket protects the runner from rain, snow and humidity, keeping them dry and comfortable during the race. At least, this is the theory.

The reality is that trail running jackets are not very waterproof, at least compared to other mountain jackets. Some of the best trail running jackets resist around 15,000 millimeters of water column, which is excellent in that range, but a little lacking for harsher outdoor activities.

BarrabesEscart Jacket by Grifone. 15000 HH waterproofing for dynamic activities.

It is important to know what type of waterproofing the jacket we are going to choose has. They are not the same as jackets with waterproofing technologies, with water-resistant coatings or with laminated membranes. Sometimes we can find everything together, but it is not common nor is it economical. It is increasingly common to find the two and a half layer membrane system in this type of garment; It combines lightness and packability in a very notable way, and the current models have greatly improved the durability problems suffered by models from a few years ago. We invite you to take a look at the article on waterproof membranes so you can discover everything there is to keep you dry in the mountains.


If it is important that, as far as possible, they prevent the entry of water, at the same time it is even more essential that they allow moisture vapor to escape to prevent the accumulation of perspiration. Breathability is equally basic in a trail running jacket, since it is an activity with very intense physical exercise where runners generate heat and abundant sweat.

A breathable jacket allows air circulation and sweat evacuation, preventing the body from overheating and promoting a feeling of comfort. Lightweight, technical fabrics, such as laminates with breathable membranes, are excellent options for maintaining the balance between waterproofing and breathability. In general, we consider correct breathability when it exceeds 10,000 g/m2/24h, with 15,000 g/m2/24h being a much more recommendable figure in very aerobic activities such as trail running.

BarrabesPocketshell Jacket W by La Sportiva. Breathability of 15000 g/m2/24H

The breathability of a trail running garment is essential and the best way to achieve this is with numerous openings and ventilation. Something as simple as having the jacket open enough for the heat we generate to escape or not wearing the hood on if it is not raining with a certain intensity can avoid major breathability problems. Let''s use all the resources at our disposal to achieve the desired balance between waterproofing and breathability.


Being lightweight is a key feature in a trail running jacket, as runners seek to minimize weight and load during the run. A lightweight jacket facilitates agile movement and does not add unnecessary burden to the runner. Advances in materials and construction techniques have enabled the creation of ultralight jackets without sacrificing protection and durability. Looking for jackets with high-quality technical fabrics and minimalist construction can ensure a more comfortable, unrestricted running experience.

BarrabesPacked size of Rab''s Windveil Jacket with 131 grams of weight.

To put figures to the data we are offering, a trail running jacket should not exceed 200 grams in weight. Obviously, we can choose heavier models whenever we are looking for superior characteristics in other areas such as waterproofing and resistance, but perhaps in those cases we should opt for trekking jacket models.

Not only will a lightweight jacket make the race or light activity we are doing easier. That our chosen model is easily packable will help us a lot in the optimal distribution of the limited space available in trail running backpacks (or on your climbing harness), finding numerous models that are capable of being reduced to the size of a fist when the we have collected.


Durability is crucial for a trail running jacket, considering the rigorous conditions and possible abrasions that runners may encounter during a race. A rugged jacket is designed with durable materials that can withstand rubbing against branches, rocks, and other trail obstacles without easily tearing or deteriorating. Unlike what happens with trekking or mountaineering jackets, in trail running it is almost impossible to find jackets with reinforcements in high-wear areas such as shoulders and elbows since being lightweight is valued more, although these protections can provide greater protection and prolong the useful life of the garment. The usual thing, more than the protections, is that the models have some fabric system to minimize the damage of a foreseeable tear, the most common being the rip stop (grid system that prevents the spread of the tear).

BarrabesSick Hood by Grifone. Aerobic jacket made of polyamide.

The problem is that the most resistant materials are usually not the most lightweight. The favorite material for making ultra-light jackets is polyester, a very lightweight material with excellent hydrophobic characteristics, but with significantly lower resistance than materials used in making waterproof jackets such as, to name only the most common of them, nylon.

Jackets made of nylon tend to be much more resistant and also more waterproof when they have an associated water-repellent system or membrane, but they are also heavier than ultra-light models that can be found today.


We have talked about technical characteristics and we cannot stop talking about ergonomics. The suitability or otherwise of a garment for the activity for which it has been designed is not only determined by the materials and their characteristics. Features such as width, range of movement it allows or details such as the ease of opening the zipper, the ventilation or the adjustment systems are essential to achieve a technical trail racing jacket that deserves to be called as such.

BarrabesMobility and adjustment possibilities to ensure comfort.

A jacket for trail running must allow arm movement and, sometimes, it is made wide enough so that it can be put on top of the backpack, thus saving time in competition by not having to take off a backpack and allowing us to protect what we carry inside from the rain. Some models allow it to be gathered in the lumbar area thanks to a large elastic area; This will make it easier for us to gather the garment at the waist without having to put it in the backpack, but we must know that the large amount of elastane used to make this possible is not the best option for a breathable garment.

Details such as preformed sleeves and hood, a certain width in the dorsal area, types of special patterns such as raglan sleeves or quick adjustments to the hem and neck will allow us to face an activity as aerobic as a race with all the guarantees of remaining with the tight garment in any condition.

What minimum requirements should a lightweight waterproof jacket have?

So, when choosing a jacket for trail running or any aerobic activity where weight is decisive, waterproofing, breathability, lightness and resistance are essential characteristics that should not be left aside. The point is to properly choose the model that best suits the type of activity we are going to carry out and also our personal tastes.

In our opinion, a jacket model with a waterproof rating of 10,000 millimeters of water column, a breathability of 15,000 g/m2/24h and a weight of no more than 200 grams usually has conditions more than adequate to carry out any mountain racing activity. With this base, from there we can adjust our demands to what we are going to need according to our experience or our needs for a specific race, being able to choose less light, less waterproof or less breathable models if we consider other options in our future activities.

Do you have more questions? Don''t stay with them. We are here to help you with whatever you need. Come visit us at our physical stores or browse our website where we will love to help you with everything you need. We are waiting for you.

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