On Running has been rolling out apparel steadily for two years, yet until now the RunMorph catalog only covered two pieces from the Swiss brand: the Race Singlet 2 and the Weather Jacket. The Ultra Jacket fills a clear gap. It's the brand's premium waterproof jacket, built for ultra-trail and foul conditions, exactly where the Weather Jacket openly admits it's only water-repellent. At RunMorph, we cross-checked a full field test published in 2025 and updated in 2026 against the official spec sheet and a verified customer review to see whether this €270 jacket delivers on its promises.
© On Running, official photo used for editorial purposes
On Running Ultra Jacket: the Swiss brand's 3rd apparel piece in our catalog
On Running built its name on shoes before expanding into a full apparel range, from racing (Race Singlet 2, already reviewed) to the versatile windbreaker (Weather Jacket, already reviewed). The Ultra Jacket sits one level above: it's the Performance/Ultra range jacket designed for the mandatory kit of long-distance trail races, where the Weather Jacket itself claims to be "weatherproof," not "waterproof." Built around a 2.5-layer Pertex Shield Air membrane rated at 20,000 mm hydrostatic head and around 25,000 g/m²/24h of breathability, it targets the top tier of ultralight rain jackets, alongside benchmarks already in the RunMorph catalog such as the Salomon Bonatti and the Compressport Thunderstorm.
On Running Ultra Jacket specs
| Feature | Value |
|---|
| Brand | On Running (Switzerland) |
| Model tested | On-Running Ultra (men's), black |
| Membrane | Pertex Shield Air, 2.5 layers |
| Waterproofing | 20,000 mm hydrostatic head (heat-sealed seams) |
| Breathability | Around 25,000 g/m²/24h (MVTR) |
| Weight | Around 100 g in size M (manufacturer/retailer figure) |
| Storage | Packs into the integrated hood pocket |
| Closure | Full-length zip, hood without drawcord adjustment (elasticated) |
| Details | Reflective elements, fitted cut, reduced chafing |
| Official price | €270 (often €195-230 on sale, depending on the retailer) |
On paper, the Ultra Jacket ticks every box for a race jacket: a featherweight build close to the lightest options on the market, a 2.5-layer membrane that skips a conventional inner lining (which saves weight), and a hood storage system that lets you compress it in seconds. That technical choice has a downside the brand openly admits: no warm lining, so zero thermal protection in cold weather. You need to add an insulating layer underneath.
Pertex Shield Air: a membrane built for hard efforts, not easy hikes
Pertex Shield Air technology relies on an air-permeable nanofiber membrane, a different approach from classic membranes like Gore-Tex Pro Shell or Raidlight's MP+, which RunMorph has already reviewed. The stated goal is to let air pass through the membrane itself while blocking liquid water, rather than relying only on micro-perforations or dedicated vent zones. A full field test backs up what the spec sheet promises: during a hard interval session in the rain, the tester says she "never got that stifling sauna effect" typical of entry-level waterproof jackets. Her base layers stayed slightly damp, but the inside never soaked through.
The Ultra Jacket's snug, "close to the body" fit is a deliberate racing choice: the brand explicitly sets it apart from a roomier hiking cut, with two ease pleats in the back so you can wear a running vest or small backpack over your clothes without discomfort. A dedicated test confirms this with a 5L vest in real conditions: "no choking or pulling sensation, the jacket covers the pack well and doesn't ride up." That's a real asset for ultra runners racing self-supported.
© On Running, official photo used for editorial purposes
RunMorph tip: an unlined 2.5-layer jacket like the Ultra Jacket keeps rain and wind out well, but adds zero warmth. In cold weather, always bring a light insulating layer to wear underneath instead of relying on the outer shell alone.
The field test: waterproofing praised in a dedicated review, but the hood flagged by a real user
Cross-checked reviews and transparency disclosure: for this article, RunMorph drew on a full, detailed field test (several running and trail outings in the women's version of the Ultra Jacket, updated April 2026, with the same construction and the same membrane as the men's version reviewed here; only the gendered cut differs). We cross-checked it against a verified customer review posted on a French retailer's product page, covering an earlier generation of the men's model (bought in November 2023, same "Ultra Jacket" product family, built around the same 20K promise). We flag this generation and cut difference openly rather than smoothing it over, because we couldn't find an independent field test dedicated to the men's version currently on sale.
On overall waterproofing and breathability, the dedicated test is unreservedly positive: through a steady one-hour downpour, the tester stayed "perfectly dry," with water that "beads on the fabric surface" and "no leaks to report, neither at the seams nor at the zip." That sharply contrasts with the verified customer review of the previous generation, which reports water gradually seeping in during a 40-minute easy run in steady but light, windless rain, and calls the waterproofing "very disappointing for a jacket that's supposed to be 20K."
The most concrete sticking point, raised independently by the negative customer review and not contradicted by the positive test (which doesn't cover this specific point), is the hood. With no drawcord (just elastic), it reportedly lets rain run down your neck, and the excess fabric in the peak soaks up water within minutes, flapping against your forehead with every stride. It's a design limitation you should know about before buying, especially for running into headwinds or in prolonged driving rain, even though it doesn't seem to undermine the overall waterproofing of the fabric and seams observed elsewhere.
© On Running, official photo used for editorial purposes
On Running Ultra Jacket vs Weather Jacket vs Salomon Bonatti Trail: head to head
| Product | Weight | Waterproofing | Positioning | Price |
|---|
| On Running Ultra Jacket | ~100 g | 20,000 mm (waterproof) | Racing, ultra-trail | €270 |
| On Running Weather Jacket | Heavier | Weatherproof (not waterproof, as the brand openly states) | Everyday versatility | €240 |
| Salomon Bonatti Trail | ~200 g | 20,000 mm | All-weather all-rounder benchmark | Mid-range |
Against its own sibling, the Weather Jacket, the difference in positioning is clear, and the brand owns it: the Weather Jacket bets on breathability and everyday comfort at the cost of only partial water protection, while the Ultra Jacket goes for full waterproofing at the cost of a higher price and less versatility outside sport (no hand pockets, very athletic cut). Against the Salomon Bonatti Trail, the all-rounder benchmark in our catalog, it comes down to weight and price: the Bonatti is about a third heavier but also much cheaper, a sensible trade-off if you're not chasing pure ultra performance.
Pros
- Featherweight (~100 g), among the lightest on the market for a truly waterproof jacket
- Top-tier breathability, little sauna effect even during hard efforts in the rain
- Packs compactly into the hood in seconds
- Works with a running vest or small pack worn over it, no discomfort
- Premium finish, partly recycled materials, effective reflective elements
Cons
- Very high price (€270 MSRP), which limits it to runners already invested in the sport
- Hood without drawcord adjustment, a weak spot in driving rain according to a verified customer review
- No thermal protection: a pure shell with no warm lining
- Thin fabric, vulnerable to brambles and abrasion off the beaten track
- Few independent field tests dedicated to the current men's version
Our verdict from the trail: who is the Ultra Jacket for?
The trail runner racing ultras with mandatory waterproof kit
This is the target profile. The weight-to-waterproofing ratio is excellent for carrying the jacket through an entire race without weighing down your pack, and it's confirmed to work worn over a running vest.
The occasional runner who just doesn't want to get caught in a shower
Big caveat. The price and very athletic positioning (no pockets, fitted cut) make it overkill for occasional use: the brand's own Weather Jacket costs less and meets that need better.
The runner who regularly faces headwinds and driving rain
Proceed with caution. The non-adjustable hood, flagged by a verified customer review of a previous generation of the same model, is worth testing in real conditions before a demanding race, since nothing confirms or rules out the issue on the current version.
For your training: a waterproof jacket at this level doesn't replace smart pace management in rain or cold, which remains the number one factor in avoiding hypothermia on a long run. Structure your trail training weeks with a plan built around your goal: explore RunMorph training plans.
RunMorph verdict
On paper and in a dedicated test, the On Running Ultra Jacket confirms its status as the weight-to-waterproofing benchmark for ultra-trail, with breathability that avoids the classic pitfall of budget waterproof jackets. The very high price and a concrete reservation about the hood, documented by a verified customer review of an earlier generation of the model, pull the score down, but it still holds up well for demanding trail runners ready to invest in their mandatory kit. A specialist's jacket, not a jacket for everyone. 7.6/10.