Best Lightweight Rain Jacket

Posted March 10, 2015 by Joel Schopp in Apparel
The Outdoor Research Helium II Jacket.

The best lightweight rain jacket is the Outdoor Research Helium II. We based this pick on lots of field testing and in depth research.

We think for most people a lightweight rain jacket is the right rain jacket. There are some people who live in Kodiak, Alaska and for those people a durable gore-tex jacket is worth every penny. For the rest of us, we usually plan to go out in the sun, but want to be able to throw on a jacket and stay dry if the weather suddenly turns into a thunderstorm. The smaller and lighter a rain jacket is the more likely it is that you will carry it with you. Lightweight rain jackets also double as lightweight windbreakers and can be thrown on as a shell layer when the wind picks up or the weather gets cold. No rain necessary.

Why We Love the Helium II


The Helium II is the lightest fully waterproof jacket you can buy. It weighs in at 6.4 ounces (180 grams). We have shirts that weigh considerably more.


The Helium II packs down into its own pocket, and it’s a small pocket. We find ourselves just leaving it in the lid of our backpack when we head out or in the glove box when we drive around town. It’s also nice to be able to take a layer off and shove it in your pocket.

Seriously waterproof

Waterproofness is measured by the pressure that a fabric will resist before it starts to leak. Anything over 5,000mm of pressure will stand up to hurricane driven rain perfectly fine. The Helium II has 20,000mm resistance, which since it is over 5,000mm is good. More likely than pressure from a hurricane, the pressure on your rain jacket would be from wet backpack straps or your arm rubbing against your side. In any case rain jackets are all plenty waterproof and your bigger concern is rain getting in through the hood opening around your face or in through the arm holes near your hands. The Helium II has an adjustable elastic cord to tighten the hood down around your face and also has elastic cuffs to keep water out around your wrists.


There are standardized tests of breathability for fabrics called MTVR(B1), which the Pertex Shield+ fabric used in the Helium II does well on. The score for those keeping track is 20,000g. The numbers aren’t that meaningful except to compare one jacket to another.

We will note that even with a very breathable jacket you will get damp if you sweat a lot. You would also get damp if you were standing under a giant umbrella without any shirt. Sweat just doesn’t evaporate well in high humidity low temperature conditions; we often call those conditions rain. We do suggest, when weather allows, unzipping your jacket to increase air circulation which will help your sweat evaporate better.

What Others Are Saying

Also very good

Montaine Minimus

The Minimus is also made with the same Pertex Shield+ fabric as the Helium II. It weighs in at a heavier 8.2 ounces, but has nicer velcro wrist closures and a higher price. Montaine has a good history of making quality products. We think the lighter weight and cheaper price of the Helium II make up for its just adequate elastic wrist closures.

Marmot Mica

Also 20,000mm waterproof and only 7oz. It also scores 20,000g in the MTVR(B1) breathability test. Marmot also has a great history of quality products. We still prefer the slightly cheaper and slightly lighter Outdoor Research Helium II.

About the Author

Joel Schopp

Joel is a a rock climber, canoer, backpacker, camper, father, skiier, programmer, swimmer, cyclist, zipliner, kayaker, and adventurer in no particular order. He is president of the Central Texas Mountaineers, Texas regional coordinator for the Access Fund, and sits on the board of the non-profit Ascend Outdoor Adventures. Joel wants you to have the best gear so you don't think about your gear and instead focus on the wonder that is the outdoors.


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