In trail, weather conditions can change rapidly and adequate protection is therefore essential. Whether it's shielding yourself from wind, rain or cold, you need to choose the right trail jacket. In this article, we explain how to choose your trail jacket.
Key takeaways:
- The choice of jacket depends on the duration of the trail and the weather.
- Waterproofness and breathability are essential criteria when choosing your trail jacket.
- A light and compact jacket is ideal for short trails, while a built-to-last and protective jacket suits ultra-trails.
- Certain details such as the cut of the jacket, its hood or its weight make all the difference.
Choosing your jacket by trail type and season
The duration of the trail helps guide runners in choosing their trail running jackets. For a short trail of two to three hours, an ultra-lightweight jacket is recommended. On fast-paced courses, the emphasis is on lightness and breathability. For a long trail of more than three hours, protection and resistance are preferable. A waterproof and windproof jacket is then ideal for tackling tough conditions.
In cold, dry weather, we encourage you to follow the three-layer principle. The trail jacket should provide light insulation to maintain good body heat without being too bulky. It should also be windproof and feature an adjustable hood for better protection. If you plan to run at night or early in the morning, choosing the right trail headlamp is equally important for your safety on the course.
In warm, humid weather, we recommend an ultra-lightweight jacket with ventilation zones to maximise airflow. It can be DWR-treated to resist splashes and made from technical materials that dry quickly and wick away moisture.
Waterproofness and breathability of the trail jacket
Waterproofness and Schmerber rating
Waterproofness and breathability are essential in trail. They directly influence comfort, particularly during races in variable weather conditions. To choose the right trail jacket, you need to find a model that offers good waterproofness while maintaining a degree of breathability. That is what membranes such as Gore-Tex and Ultrashell have been designed for.
The Schmerber rating measures the waterproofness of a trail jacket. Expressed in millimetres, it measures a jacket's ability to resist water penetration. A rating of 10,000 mm means the fabric can withstand the pressure of a column of water 10,000 mm high.
Waterproofness of a trail jacket:
- 5,000 to 10,000 mm: light to moderate protection, ideal for light or intermittent rain.
- 10,000 to 20,000 mm: moderate to high protection, suited to heavy rain and wet conditions.
- Above 20,000 mm: very high waterproofness, used in extreme conditions.
Breathability, MVTR and RET
Breathability is a fabric's ability to evacuate the water vapour and sweat generated by the body during exertion. It prevents the feeling of discomfort during effort. The breathability of a trail jacket can be evaluated using MVTR and RET.
MVTR (Moisture Vapor Transmission Rate) measures the amount of water vapour a fabric can evacuate over a 24-hour period, expressed in grams per square metre. A higher value means better breathability.
MVTR breathability of a trail jacket:
- 5,000 to 10,000 g/m²/24h: moderate activity in temperate conditions.
- 10,000 to 20,000 g/m²/24h: suited to intense effort with effective moisture management.
- Above 20,000 g/m²/24h: highly breathable, ideal for long-distance races or hot and humid conditions.
RET (Resistance Evaporative Transfer) measures the resistance a fabric opposes to the evacuation of water vapour. A low RET indicates better breathability.
RET breathability of a trail jacket:
- Below 6: highly breathable, perfect for intense activities.
- Between 6 and 12: suited to breathable garments in moderate conditions.
- Between 12 and 20: limited breathability.
- Above 20: fabric considered non-breathable.
Other criteria for choosing your trail jacket
Other elements help you choose the right trail jacket. A stretch fabric improves comfort and freedom of movement, particularly during long or technical races. The cut of the jacket should match your body shape while allowing a wide range of movement.
An adjustable hood offers good protection and adapts to changing conditions. It must be deep enough to protect you from the rain, yet flexible enough to avoid restricting your vision. A model with elastic cinching or a drawcord system keeps it in place even in strong wind.
In a race, every gram counts. For a short trail, opt for a jacket weighing 100 to 200 g. It should be as lightweight as possible, while still offering a minimum of protection. For an ultra-trail, you'll need a more built-to-last jacket, between 200 and 350 g. This offers solid protection while remaining light and compact. In the same way, choosing the right trail pack is essential to optimise your comfort and avoid unnecessary bulk.
Finally, some ultra-trails impose specific requirements on gear. While each race has its own criteria, the trail jacket must generally feature a waterproof and breathable membrane (10,000 Schmerber and RET below 13), an integrated or attached hood, and must not have any sections made from non-waterproof fabric outside of ventilation zones.
Choosing the right trail jacket depends on the duration of the race and weather conditions. Lightness, waterproofness and breathability are the key criteria. In all cases, opt for a model suited to your activity to combine protection and comfort on your outings.
