When you buy through our links, we may receive a commission. A waterproof rain jacket is an essential kit component for hikers, backpackers, and a multitude of other outdoor adventurers. As with any gear category, there are varying levels of effectiveness within it, including breathability, comfort, and durability. The most important measure of any rain jacket, though, is how well it seals out moisture—and the term “waterproof” is more nuanced than you might think.