The Arc'teryx Atom LT employs the classic strategy of hybrid construction to balance weather resistance and breathability. Thin, stretchy panels on the sides vent the heat while less breathable material on the front and back protect you from the elements; the result is a jacket that is not as breathable as the most breathable competition, but more weather resistant at nearly the same weight. The Atom LT is lighter weight than the other jackets in the Arc'teryx line-up that we have reviewed but is not as breathable or durable.
This jacket has many fans because of its comfort, breathability, and style.
Arc'teryx uses 60 g/m2 of its proprietary Coreloft insulation for the Atom LT. It is much warmer than its lightweight little brother, the Arc'teryx Atom SL, which has 40g/m2 Coreloft only in the torso, and around half as warm as the Arc'tery Atom AR, which has Coreloft 120 insulation in the torso. Worn as a mid-layer, the Atom LT is similar in warmth to the other active mid-layers made by other companies. As an outer layer, the warmth that its insulation holds in is counteracted by the easy breathability of the fleece side panels. When cold winds blow, you'll need a lightweight shell layer or wind jacket over this jacket to remain warm.
Stretchy breathable side panels make it more comfortable to wear this jacket while hiking with a backpack or a crash pad on.
Weight & Compressibility
Our size small test model tips the scales at 12.2 ounces, and Arc'teryx claims that a size medium will be about 14.6 ounces, which is about average for a jacket of this design. While the Atom LT can compress quite small, it does not stow away in one of its pockets. We wish that we could stuff it away and clip it to a harness. Fortunately, it breathes and moves so well that you are less likely to take it off while climbing.
This jacket compresses to a packable size but doesn't stow away in its own pocket. Here we've tucked it into the hood and tightened the cinch cord.
Arc'teryx has long impressed us with its attention to detail and thoughtful features, and the Atom LT doesn't disappoint. It has comfy, streamlined elastic cuffs that fit snugly and keep the heat in, and it's little details like this that earn the Atom LT a high score in the comfort metric. Great mobility made this one of our favorite layers for bouldering in cold weather.
We love the adjustable hood on this model. A single cord lock at the back of the head tightens the elastic cord, which extends to the front of the hood and up over the brow. The main zipper has a nicely shaped plastic pull that is hooded by a small fabric flap under the chin when fully closed.
The two hand pockets are lined with a soft microfleece and provide plenty of room for gloved hands. The large chest pocket on the interior of the jacket has ample storage, but the pocket is lower than most, and it felt more like a stomach pocket. The cuff design incorporates stretchy, wedge-shaped panels over the inner wrist. These seal in warmth with a snug fit and are low profile for sliding your glove over top. To seal in the warmth, the elastic hem cinch can be tightened and secured at either hip with a cord lock.
Arc'teryx has always impressed us with their attention to detail. We loved the large zipper pull and the comfy, low profile cuffs.
This hybrid contender is designed with breathability as a higher priority than weather resistance. While this piece has an effective DWR treatment that beaded water in a light drizzle, the nylon outer fabric and fleece side panels begin to absorb water within a few minutes. This jacket functions perfectly as a mid-layer and is a nice choice for a terminal layer in calm and dry conditions. When the wind blows or it starts to drizzle, layer your waterproof breathable rain jacket or hardshell over top.
A DWR finish keeps light rain beading off the shell fabric, but water will soak right through stretchy side panels underneath the arms.
The Arc'teryx Atom LT employs a hybrid construction. The Tyono fabric that Arc'teryx uses for the Atom LT's main outer fabric provides better air-flow than more weather-resistant fabrics. At the same time, other hybrid layers received better overall breathability scores.
For a long time, this hybrid construction style was the best approach to breathability, but now the newer insulation technologies found in the whole crop of active insulated stretch jackets currently offer state-of-the-art comfort and breathability during high energy activities.
The Atom LT has great mobility and breathability for climbing, running and skiing.
This jacket has a soft matte finish and an athletic cut. It lacks the techy shine of some of the other jackets in the review, and it looks fine for wearing around town, though maybe not in bright yellow like our tester piece. Fortunately, it is available in eight different colors, so there's likely something that will make everyone happy.
The Arc'teryx Atom LT is a bit pricey, but it's more affordable than competing models from Patagonia. The fleece-lined pockets and adjustable hood are features we love that don't appear on many of the competitors, even ones that are more expensive. If you can afford it, we feel it presents pretty decent value.
Due to its comfy fit and fine features, this is a favorite of several of our testers. The low profile cuffs and low bulk fit make it an excellent mid-layer for skiing, climbing, and cold weather backpacking. Designed to regulate temperature and moisture during high energy output, it's a fine choice for cold weather trail running, and stop and go cold activities like bouldering.