The single best trail running jacket does not exist. It all depends on the weather you face and your level of exertion. Three categories cover virtually every outing: waterproof jackets for heavy rain and alpine exposure, windbreakers for wind and passing showers, and warm mid-layers for dry, cold conditions. Choosing the right piece means pinpointing your specific terrain requirements.
This guide breaks down the Cimalp range by use case. You will find the metrics that truly matter—Schmerber waterproof ratings, breathability, weight, and cut—alongside a model-by-model breakdown and a clear comparison table. The goal is straightforward: helping you pick the exact jacket built for your runs!
Our recommendation at a glance
Start by choosing based on conditions:
- Rain, alpine terrain, ultra racing: a waterproof jacket with a membrane. Our flagship model is the STORM PRO +, engineered to be worn directly over a pack.
- Wind, brief showers, fast runs: a lightweight, packable windbreaker such as the WIND or SKIN.
- Dry cold, winter, heat regulation: a breathable, warm mid-layer such as the BLIZZARD fleece.
Most regular trail runners eventually own all three. They do not replace one another; they complement each other depending on the season and race conditions.
The 3 types of trail running jackets: waterproof, windbreaker, mid-layer
Every trail running jacket serves a specific purpose. The three-layer system structures this choice. The base layer wicks away sweat. The mid-layer provides thermal warmth. The outer shell protects against rain and wind. A trail jacket serves either as an outer layer—waterproof or windproof—or as a warm, breathable mid-layer.
Mixing up these functions leads to two classic mistakes: reaching for a windbreaker in pouring rain leaves you soaked within the hour, while throwing on a thick hardshell on a cool, dry run causes overheating and rapid chilling once you stop. The right approach is to identify your primary challenge—rain, wind, or cold—and pick the dedicated gear. All three work together: layer a windbreaker or waterproof jacket over a mid-layer when conditions turn severe.
#1 Waterproof jackets (hardshell)
A waterproof trail jacket shields against durable rain using a technical membrane and fully taped seams. It is the definitive safety piece for long, exposed mountain runs. It is evaluated on two metrics: waterproofness, measured in Schmerber, and breathability, rated in g/m²/24h.
What Schmerber rating to look for
Schmerber measures the water column a fabric can withstand before moisture penetrates. The higher the number, the longer the protection holds up.
| Level | Intended use |
|---|---|
| 10,000 Schmerber |
Waterproof, including in heavy downpours. Reaches its limits during sustained multi-hour rainfall or intense torrential storms. Minimum required by UTMB regulations. |
| 20,000 Schmerber |
Full day in the rain. Recommended level for regular trail runners. |
| 30,000 Schmerber and above |
Severe conditions, prolonged rainfall, high exposure. |
Breathability is just as crucial. A highly waterproof jacket with poor breathability will leave you soaked from sweat on steep climbs. Look for a fabric that actively expels moisture vapour during hard efforts to prevent internal condensation. Two additional factors should guide your choice: weight determines pack volume when stowed away, and the cut must allow you to wear it over a pack, offering ample back coverage and sleeves that protect your wrists in motion.
The Cimalp waterproof selection
The STORM PRO + is our most advanced waterproof jacket. Built with the 3-layer Ultrashell membrane, it features 20,000 Schmerber waterproof protection and 80,000 g/m²/24h breathability. This breathability level places it among the highest-performing jackets on the market. It features water-repellent YKK Aquaguard zips and a fitted hood with a stiffened peak. Above all, it is designed to be worn over a trail running pack, maintaining easy access to soft flasks and pockets. Available for men and women, at £209.90.
The STORM PRO (£189.90, 290 g) features the same 3-layer Ultrashell membrane, matching the 20,000 Schmerber and 80,000 g/m²/24h ratings of the STORM PRO +, in a classic trail fit.
The STORM (£139.90, 225 g) is built with 2.5-layer Ultrashell Slim rated at 10,000 Schmerber—a lighter build that fully complies with ultra race regulations. Men and women each benefit from dedicated fits. To explore the full collection, check out our waterproof trail running jackets.
An often-overlooked point: accessing your gear in the rain. We cover this in detail in our guide to trail running in the rain.
#2 Windbreaker jackets
A windbreaker protects against wind and brief showers, without the full barrier of a waterproof membrane. It is lighter, more breathable, and packs easily into a pocket or pack. It is the outer layer for fast-paced outings and changeable, but not heavily rainy, conditions.
The difference with a waterproof jacket comes down to duration. A water-repellent windbreaker beads water and fends off a light shower. Under sustained, prolonged rain, it eventually lets moisture through. In return, it is more breathable and lighter. For a fast trail runner prioritising low weight, it is often the most worn jacket throughout the year.
Packability is essential here. A good windbreaker folds away into its own pocket, fitting neatly in your hand or in a pack compartment. Pull it out when the wind picks up on an exposed ridge, and stow it away as soon as temperatures rise. It is the ideal choice for transitional seasons and unpredictable weather.
At Cimalp, the WIND (140 g, £99.90) relies on stretch CimaWind fabric, a water-repellent DWR finish, and wind protection engineered for gusts from 60 to 90 km/h.
The SKIN (115 g, £74.90) takes the ultra-lightweight approach even further: it packs down to palm size, hood included. A windproof gilet completes the range to shield the core without restricting arm movement.
#3 Warm mid-layer jackets
The mid-layer provides warmth. In trail running, this comes as a technical, breathable, stretch fleece worn over the base layer and, if necessary, under an outer jacket. Its job is not rain protection, but locking in body warmth in cold, dry weather while transferring sweat outwards.
It is primarily used in winter, at high altitude, or on long runs alternating between high output and stops. A good thermal trail jacket remains low-bulk, refuses to hold moisture, and pairs seamlessly with a windbreaker or waterproof jacket when conditions turn.
The BLIZZARD (370 g, £84.90) is our warm trail mid-layer—cosy, stretchy, and athletic-cut to be worn either standalone or under an outer shell.
Our proprietary technologies: Ultrashell and CimaWind
Cimalp develops its own proprietary membranes rather than off-the-shelf options. Two core technologies define our trail range.
Ultrashell is our waterproof-breathable membrane. On the STORM PRO +, it features a 3-layer construction: an outer fabric, the membrane, and an inner lining that shields the membrane while enhancing next-to-skin comfort. This design delivers the ideal balance of durable weatherproofing and active moisture vapour transfer.
CimaWind is our proprietary windproof fabric, used across the SKIN and WIND models. It blocks the wind while remaining highly breathable, designed for outings where you need protection without overheating. Choosing the right range comes down as much to fabric technology as it does to waterproof ratings.
Which jacket for each season and weather condition
The right model shifts with the season. Here is a quick breakdown by conditions.
| Conditions | Recommended jacket | Cimalp model |
|---|---|---|
| Sustained rain, ultra racing, alpine terrain | Waterproof | STORM PRO + |
| Wind, brief showers, fast-paced runs | Windbreaker | WIND, SKIN |
| Dry cold, winter | Warm mid-layer | BLIZZARD |
| Cold and rain combined | Mid-layer + waterproof | BLIZZARD under STORM PRO + |
In winter, layering is key. Layer up or down depending on exertion and exposure, packing away your windbreaker or waterproof into your pack whenever weather permits.
For ultras and racing: mandatory UTMB gear
On UTMB World Series events, a hooded waterproof jacket is part of the mandatory kit. Failing to carry one or using non-compliant gear results in immediate disqualification, just like missing a headlamp or survival blanket. The jacket must feature an integrated hood and a waterproof membrane rated at least 10,000 Schmerber, with fully taped seams. A 20,000 Schmerber rating and high breathability are strongly recommended.
The STORM PRO + delivers 20,000 Schmerber—double the minimum required—along with a stiffened peak hood. The STORM, approved for ultra running, meets the mandatory 10,000 Schmerber threshold while weighing in at a light 225 g. Always check your race regulations before the start, as specific requirements may vary between events.
Official source: UTMB Mont-White mandatory gear and 2026 regulations.
Cimalp range comparison table
| Model | Category | Technology | Waterproof rating | Breathability | Weight (M) | Price |
|---|---|---|---|---|---|---|
| STORM PRO + | Waterproof | Ultrashell 3-layer | 20,000 Schmerber | 80,000 g/m²/24h | 296 g (M) / 255 g (S) | 209,90 € |
| STORM PRO 4 H | Waterproof | Ultrashell 3-layer | 20,000 Schmerber | 80,000 g/m²/24h | 290 g | 189,90 € |
| STORM 4 H | Lightweight waterproof | Ultrashell Slim 2.5 layers | 10,000 Schmerber | 12,500 g/m²/24h | 225 g | 139,90 € |
| WIND | Windbreaker | CimaWind (water-repellent DWR) | Not waterproof | Highly breathable | 140 g | 99,90 € |
| SKIN | Ultra-lightweight windbreaker | CimaWind (water-repellent DWR) | Not waterproof | Highly breathable | 115 g | 74,90 € |
| BLIZZARD | Warm mid-layer | Stretch thermal fleece | Not applicable | Breathable (Warm insulation) | 370 g | 84,90 € |
FAQ
Waterproof, windbreaker or mid-layer: which one should you choose?
Identify your primary need. Persistent rain: waterproof. Wind and brief showers: coupe-vent. Dry cold: warm mid-layer. All three can be combined when conditions get tough.
What Schmerber rating should you look for in trail running?
10,000 Schmerber is sufficient for light rain and meets the UTMB minimum requirement. 20,000 Schmerber provides full-day protection in continuous rain.
Which trail running jacket for winter?
In winter, combine a breathable warm mid-layer with an outer shell matched to the weather. In dry, cold conditions, a thermal jacket is often all you need. In rain or snow, layer a waterproof jacket over the top.
What is a mid-layer in trail running?
This is the insulating layer that traps body heat while wicking away sweat. Wear it over your base layer and, when needed, beneath a windbreaker or a waterproof jacket.
Which jacket meets mandatory UTMB gear requirements?
A hooded waterproof jacket with a membrane of at least 10,000 Schmerber and fully taped seams. A 20,000 Schmerber rating is recommended. Always check your event regulations on the official UTMB website.
Which women's waterproof trail running jacket should you choose?
The STORM range includes dedicated women's fits, including the STORM PRO +. The selection criteria remain the same: waterproofness, breathability, and a fit tailored for wearing over a pack.
Photo credits: Cyrille Quintard (outdoor photos)
