Our Verdict
Our Analysis and Test Results
If you need an ultralight and packable rain protection later, the Outdoor Research Helium UL is our favorite. The 2.75-layer construction uses a Toray Dermizax membrane with an ultralight, 15-denier ripstop material. We consider this our in-case-of-emergency rather than the jacket for sustained conditions, since it's so lightweight and isn't really made for hardcore, regular wear and tear use.
Water Resistance
While the Helium UL offers excellent water resistance for its featherweight construction, we think it's best suited for those seeking an ultralight, just-in-case layer that will get them through an unexpected afternoon thunderstorm. Our testers in California love this shell for the typical short-lived afternoon thundershower in the High Sierra. The Aquaguard zippers on the main zipper and hand pockets kept water from sneaking into the jacket, while the moldable wire hood brim protects your face.
Despite the added layer of protection (2.75-layer instead of the previous 2.5-layer), we still think of the Helium UL as a lightweight emergency rain or wind layer, rather than a super waterproof design built for gnarly weather conditions — meaning, this is not the everyday rain jacket we'd recommend for folks who live in perpetually rainy climates. Though it has an adjustable hood and a cinch cord at the waistline to help seal out rain, the minimalist construction only includes partially bonded elastic cuffs rather than fully adjustable velcro closures, a detail only noticeable when you're moving your arms over your head, like climbing or scrambling when the weather worsens. During intermittent storms, we think you'll be glad you packed this layer for a little extra warmth and water-resistant protection.
Breathability
Unfortunately, the Helium UL isn't really designed with breathability in mind. The minimalist construction forgoes ventilation features like pit vents, mesh-lined pockets, or a two-way main zipper in exchange for lightweight, stripped-down performance. While opening up the main zipper and hand pockets can somewhat increase airflow, the fabric still stuck to our skin when we got warm while huffing and puffing uphill.
The elastic-bound wrist cuffs are actually appreciated for increased breathability as the larger fit allowed more airflow, especially when swinging our arms on trail runs, but the lack of overall ventilation caused us to dock a few points from the design. We essentially have to open up the main zipper to allow more airflow, which is fine during a light drizzle but not ideal in more sustained weather. This jacket is definitely better suited for those seeking ultralight packability over breathable performance.
Comfort and Mobility
Previous iterations of the Helium featured a super slim cut that felt a little restrictive and difficult to layer. However, this model's updated fit aims to increase comfort without adding extra ounces. Even testers with larger shoulders found the jacket roomier and less restrictive, passing our objective stretch test with flying colors. In fact, it's so light, you almost forget that you're wearing a piece of outerwear, which is just one of the reasons we love this jacket for trail runs, bike rides, or as our emergency layer for climbing missions in the alpine.
We love the updated fit that allows a better range of motion for everything from fast-paced outdoor activities to hikes or dog walks when you're just not sure about the weather. While the interior felt decent next to bare skin, we wish the interface with the chin was a little more comfortable. That said, we only noticed this on colder days when we had everything cinched tight. Without the hood on, the neck is wide enough that you don't really notice it. The feather-like construction includes just the slightest amount of adjustability through a cinch cord on the waistline as well as one of the wire-brimmed hood, but the wrist cuffs are only adjustable via partial elastic, so we couldn't fully tighten them down when conditions got worse. However, the wrist cuffs still leave space for an extra layer.
Weight
The ultralight weight is the greatest appeal of the Helium UL's design. Weighing in at 5.5 ounces for a women's size medium, it's so lightweight and packable that it's a no-brainer as to whether or not to toss it into your daypack or overnight pack for a longer trip into the mountains. The latest design features a 2.75-layer construction that has even more sustained performance during sporadic rain conditions.
The jacket packs easily into its own zippered left-hand pocket, and measures only 5 1/2" by 8" by 2", literally the smallest and most packable jacket that we're testing. The stow pocket also features a functional attachment point for those wanting to use this as an emergency climbing layer or clip it to their backpack for easy access in bad weather. If you're counting every ounce of gear in your kit, you're gonna love this feather-light design that's super packable and the perfect emergency layer for your next mission.
Construction Quality
The Helium is on par with some of the highest-quality designs we've tested. The construction is super thin, lightweight, and similar to a windbreaker with enough water resistance to keep you dry during an unexpected afternoon thunderstorm. The adjustable hood and cinch cord hemline are streamlined to limit weight without reducing quality and function. And we love the Aquagaurd zippers on the main zipper and hand pockets, which we found effective in keeping moisture away from the interior. All the zippers run smoothly, and we love thoughtful design features like a small wire brim for better hood coverage.
Outdoor Research even included reflective logos to increase visibility for those who find themselves wearing the jacket at dawn and dusk. We had no issues with the lightweight material during our testing period, but keep in mind that this is a thin and lightweight fabric with ultralight zippers and minimalist features, so you'll want to treat it with care. The “adjustable” wrist cuffs are only adjustable via a small elastic band, which could stretch out over time, rather than an adjustable velcro wrist closure. For this reason, we love the Helium UL as our lightweight emergency layer, but wouldn't recommend it for waterproof protection on burly backcountry missions.
Should You Buy the Outdoor Research Helium?
If you're looking for an everyday rain jacket for your commute or for running errands, this is not the jacket you're looking for. But if you're counting every ounce in your kit and looking for a feather-light emergency layer for staying dry in sporadic afternoon thunderstorms, you're gonna love the Helium UL. It's lightweight, with quality construction and includes protective features like watertight zippers, sealed seams, a wire-brimmed adjustable hood, and a comfortable fit. It's the lightest, most packable design for those seeking a just-in-case layer when the forecast isn't ideal. The jacket is backed by Outdoor Research's infinite guarantee, and we think it's great for minimalists who are packing for fast and light adventures.
What Other Rain Jackets Should You Consider?
The Helium UL is our favorite lightweight and packable design, but it isn't great for sustained downpours. If you need a jacket you can count on, we highly recommend the Arc'teryx Beta SL. This jacket provides the best waterproof performance of all the jackets in our lineup. If you need something more affordable, the Black Diamond Fineline Stretch is another solid rain jacket designed for lightweight mountain adventures. It's thicker, and the fabric is stretchier, but the packability is exceptional. And if you just want something best-suited for everyday, casual use or work commutes, we love the Patagonia Outdoor Everyday Rain Jacket.
| Awards | Most Packable Design |
|---|---|
| Price | $225 List Check Price at Backcountry |
Overall Score ![]() |
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| Star Rating | |
| Bottom Line | This ultralight layer is best-suited for those seeking an emergency layer that easy to pack and requires very little space in your pack |
| Pros | Super packable and lightweight, great mobility, wire brim hood, comfortable fit, excellent wind protection, watertight zippers and fully sealed seams |
| Cons | No vents, limited water resistance and breathability |
| Rating Categories | Outdoor Research Hel... |
| Water Resistance (45%) | |
| Breathability (20%) | |
| Comfort and Mobility (15%) | |
| Weight (10%) | |
| Construction Quality (10%) | |
| Specifications | Outdoor Research Hel... |
| Number of Fabric Layers | 2.75 |
| Material and Waterproof Membrane | Toray Dermizax 2.75-layer 100% nylon 15-denier ripstop 61 g/m² shell |
| Measured Weight (Size Small) | 5.5 oz |
| Pockets | 2 zippered hand |
| Pit Zips | No |
| Pit Zip Length | No |
| Stows into Pocket | Yes |
| Carabiner Loop in Stow Pocket | No |
| Helmet Compatible Hood | No |
| Hipbelt Friendly Hand Pockets | No |
| Additional Features | Adjustable hood, YKK Aquaguard Zipper, elastic cuffs, adjustable drawcord hem, carabiner loop, key clip, reflective logo |







