When the weather goes wild, your waterproof jacket becomes your best ally on the trails. But you’ve got to know how to pick it. Whether you’re tackling your first trail or aiming for a tough ultra, a good jacket can be the difference between quitting and finishing.
Here’s everything you need to know to choose a high-performance, breathable, and regulation-compliant waterproof jacket for big races.
The role of a waterproof trail jacket
A trail jacket has several essential functions:
- To protect you from rain, wind, and cold
- Let your body breathe despite the effort
- Stay compliant with official race rules like UTMB® or Diagonale des Fous, which require a waterproof jacket with a hood and at least 10,000 Schmerber.
But watch out: not all jackets are equal. Here’s how to decode the technical specs.
Waterproof, water-repellent, windbreaker: what’s the difference?
Windbreaker
A windbreaker stops cold air from sneaking in, especially when you’re sweating. It brings comfort but isn’t always waterproof.
Water-repellent
The fabric makes water slide off the surface. That’s enough for drizzle or light snow, but not for real rain. Water repellency doesn’t replace waterproofing.
Waterproof
Here, we’re talking real protection. It’s measured in Schmerber (water column supported before it seeps through). Here are some benchmarks:
- 5,000 Schmerber: light rain
- 10,000 Schmerber: heavy rain (required level in races)
- 15,000 to 25,000 Schmerber: protection in extreme conditions
The higher the number, the longer you stay dry.
At Raidlight, we use the MP+ membrane (our in-house tech equivalent to Gore-Tex®) for the perfect mix of waterproofing, breathability, and lightness.
Breathability: stay dry even when you’re sweating
Running in the rain, sure. Drenched in your own sweat? No thanks. That’s where breathability comes in: the jacket’s ability to get rid of internal moisture.
Two indices are used:
MVP (Moisture Vapour Permeability)
This is the most common. It measures the amount of water vapor expelled in 24h (in g/m2/24h).
- 5,000: barely breathable
- 10,000: decent
- 20,000: very breathable
- 40,000+: excellent
RET (Resistance Evaporative Transfer)
Here, the lower the better.
- RET > 20: not breathable
- RET < 6: very breathable
Example: our Ultralight MP+ 3.0 jacket shows 25K/50K (25,000 Schmerber and 50,000 MVP): comfy on an ultra, even in a downpour.
The details that set it apart
When two jackets have the same specs, it’s the little extras that make the difference:
- A well-fitted hood
A must-have. Protects your neck and stops water from running down it.
- Waterproof pockets
For your phone, keys, or a snack. If they close tight, you stay chill.
- Watch window
No need to roll up your sleeve to check your watch. Handy.
- Shoulder reinforcements
Wearing a backpack? Silicone reinforcements stop the rubbing.
How do you take care of your waterproof jacket?
No need to wash it after every outing. Better to air it out, rinse with cold water if needed, and let it dry in the open air.
If you really have to wash it:
- Choose a gentle program (ideally "sport" or "hand wash")
- Use a special detergent for technical clothing
- Close the zips, empty the pockets
- Avoid strong spin, tumble dryer, radiator or ironing
The less you wash it, the longer it lasts.
Raidlight jackets: for all trails, all weather
At Raidlight, all our jackets are equipped with the MP+ membrane and approved for major races (UTMB®, UT4M®, Diagonale des Fous®).
Ultralight MP+
- Ultra light, waterproof and breathable (25K/50K)
- 12L backpack gusset
- Perfect for ultra-performance
Top Extreme MP+
- 20K/20K
- Watch window, shoulder reinforcements, ergonomic hood
- Perfect for long-term commitment
In short:
A good trail jacket is the one that keeps you dry both outside and inside, lets you move freely, and meets the demands of your terrain.
Take your time to choose. On an ultra, your jacket becomes your refuge.
