In a Nutshell
The lightest waterproof jacket currently available is the Outdoor Research Men’s Helium II Jacket. The jacket weighs just 6.4 oz and is made with 100% Nylon and a 2.5 layer 30D Pertex Shield DS rip-stop fabric.
There is also a women’s version of the Helium II.
A waterproof jacket is an item you hope you won’t need when travelling, but is something you never want to be caught without. That’s why an ultra-lightweight option is a perfect way to assure you’ll never be exposed or have to lug around a cumbersome coat. The Helium II is the lightest waterproof jacket out right now and it weighs about half a pound, a full 10 oz lighter than most rain jackets marketed as “lightweight.”
It is a pared down jacket, so it doesn’t include any pit zips and only has one pocket. It is very compressible, and can easily fit in a backpack or even a sweatshirt pocket. The lone pocket is located on the upper chest. Personally, I prefer hip pockets to put my hands in when its cold. The chest pocket is an advantage if you have a hiking backpack strapped at your waist. The Helium II also has an adjustable hood and a 7.5″ internal stormflap.
The Nylon material is breathable and will keep you dry in all but the fiercest of storms. It cuts the wind well for an ultra-lightweight jacket, although not as well heavier waterproof jackets. The elastic cuffs are a nice touch.
Outdoor Research also offers the Helium HD, which is a heavier-duty waterproof jacket. It has a Pertex Shield+ that is both breathable and waterproof. It’s wire-brimmed Halo hood does a better job of shielding your face than the standard edition. It also comes with a few extra pockets, which do increase the weight. It is still very light at 9.3oz.
The Marmot Minimalist Jacket is another great lightweight waterproof option. It is GORE-TEX with Paclite technology. The Marmot Minimalist comes with pit zips, hand pockets, and an adjustable hood. As with the Helium HD, these extra features push its weight close to 10oz. It costs about $170.