Ultralight Rain Jacket
Outdoor Research Helium II Jacket
$159, 6 oz. (men’s medium)
Sizes: men’s XS-XXL, women’s XS-XL
backcountry.com
When the cool mist got heavy enough that I needed more than a base layer on the first morning of a five-day backpacking trip on the Wonderland Trail in Mount Rainier National Park, I pulled on my Helium II Jacket and stayed dry until the sun came out a few hours later—at which point I kept this ultralight shell on to fend off the cool alpine wind. Wearing it in wind at other times on that hike and on local trail runs in mixed weather, this featherweight demonstrated its value as one of today’s best ultralight, waterproof-breathable rain jackets.

That backpacking trip on the Wonderland Trail illustrates a major advantage of the Helium: It’s one of the lightest and most packable waterproof, fully seam-taped, and breathable rain jackets out there today. With a forecast was for mostly dry weather, I could forego carrying a heavier and bulkier rain jacket—and mostly carrying it rather than wearing it—knowing the Helium would give me all the protection I needed at about half the weight, bulk, and cost of a high-quality, technical rain shell.
Constructed from 30-denier ripstop nylon, waterproof-breathable Pertex Shield, the jacket employs Diamond Fuse technology, which uses yarns with diamond-shaped filaments that lock together, lending it relatively good durability and snag-resistance for a fabric this light and improving its water-beading properties. Still, this fabric is ultralight: It will stand up to wearing a backpack over it, but likely tear too easily for hiking off-trail in forest or rock climbing.
Breathability is just okay. When hiking uphill on the Wonderland Trail, carrying a full pack, the Helium got a little clammy inside but was tolerable. On autumn trail runs of up to two hours in my local foothills, I could keep the hood up in strong, cold wind without building up much moisture inside—mostly because I wasn’t overheating. In other words, while it doesn’t breathe as well as the best ultralight, non-waterproof wind shells, it performs as well as needed in most hiking and trail-running circumstances in which I’d wear it—and offers the reassurance of waterproof protection.
The jacket feels very comfortable as soon as you put it on, with a close fit that has space to layer midweight insulation under it. The adjustable hood uses a single drawcord in the back and wraps snugly around your head, although the small brim offers negligible face protection.
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The shell stuffs into its one zippered chest pocket—which is large enough for a smartphone—packing down to the size of a large coffee mug (and has a carabiner loop). The waterproof front zipper, like all such zippers, moves a little more slowly than standard zips. The elasticized hem and cuffs, while not adjustable, adequately seal out drafts.
With mediocre breathability and durability and a minimalist hood, the Helium II certainly isn’t as versatile as a fully technical, all-conditions rain shell. (See my picks for “The 5 Best Rain Jackets for Hiking and Backpacking.”) But it is about half the weight and bulk of most high-quality rain shells.
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The Outdoor Research Helium Pants ($119, 5.4 oz.), made with the same 30-denier ripstop nylon Pertex Shield, have elasticized waist and cuffs with 12-inch zippers for pulling them over boots, and stuff into the zippered rear pocket.
The Verdict
For lightweight and ultralight backpackers, dayhikers, trail runners, and bike commuters who need a just-in-case ultralight shell for wind and rain, the Outdoor Research Helium II Jacket delivers waterproof protection and okay breathability in a compact package that’s a good value for this degree of performance and low weight.
BUY IT NOW You can support my work on this blog by clicking any of these affiliate links, at no cost to you, to purchase the men’s or women’s Outdoor Research Helium II Jacket at backcountry.com or moosejaw.com, the men’s Helium II Jacket at outdoorresearch.com, or the women’s Helium II Jacket at outdoorresearch.com. You can purchase the men’s or women’s Outdoor Research Helium Pants at backcountry.com or moosejaw.com, or the men’s Helium Pants at outdoorresearch.com, or the women’s Helium Pants at outdoorresearch.com.
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See my review of “The Best Ultralight Hiking and Running Jackets” and “The 5 Best Rain Jackets for Hiking and Backpacking,” and all of my reviews of ultralight wind shells, ultralight rain jackets, and outdoor apparel at The Big Outside.
NOTE: I tested gear for Backpacker magazine for 20 years. At The Big Outside, I review only what I consider the best outdoor gear and apparel. See my Gear Reviews page at The Big Outside for categorized menus of all of my reviews and my expert buying tips.
—Michael Lanza
Whether you’re a beginner or seasoned backpacker, you’ll learn new tricks for making all of your trips go better in my “12 Expert Tips for Planning a Wilderness Backpacking Trip,” “A Practical Guide to Lightweight and Ultralight Backpacking,” and “How to Know How Hard a Hike Will Be.” With a paid subscription to The Big Outside, you can read all of those three stories for free; if you don’t have a subscription, you can download the e-guide versions of “12 Expert Tips for Planning a Wilderness Backpacking Trip,” the lightweight backpacking guide, and “How to Know How Hard a Hike Will Be.”
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