The Arc’teryx Atom LT is a hybrid construction that attempts to balance breathability with weather resistance. Similar to the Proton LT, it has stretchy fleece side panels on the sides to help vent heat while the less breathable material on the front and back provides protection from wind and water.

The Atom LT isn’t as breathable as other competitors on the market but it is much more weather resistant than the competition. The LT in the name refers to being part of the lightweight range in Arc’teryxs lineup. If you’re not familiar with the variations in Arc’teryx’s lineup, you can see what each abbreviation means here.

Design,  & Durability (Rating: 80%)

There were some subtle updates in the 2020 Atom LT that made for some nice improvements. The slight changes in the cuff, fit and fabric were great. The attention to detail on this jacket like most Arc’teryx clothing is perfect, the logo is well stitched, and the soft lining and smooth exterior make the jacket feel great. The outer lining of the jacket is around 20 denier, which is about as thin as the previous version of the jacket, but you’ll still want to be careful around sharp objects. Scuffing on rocks is a non-event, I’ve spent a day or two climbing in this jacket until it got too hot and you could barely tell I had been dragging this jacket all over granite and sandstone. There’s a new loft in this version of the jacket as well, called Coreloft, which is meant to last longer than other insulation fibres.

I had the hooded jacket to test which was great as I’m not sure why anyone would buy a non-hooded version for use outdoors, could just be me though. The hood comes in handy if you’re sitting or standing still for a period of time as well as being useful if it’s a little bit chilly. That said, the Arc’teryx Atom LT isn’t really something you’d sit around camp in as it needs a bit more insulation, it could be used under a shell for extra warmth for cold nights or long stints of no movement. Moving in the Atom LT is where it excels, it manages to keep you warm enough to feel comfortable but not too warm that you turn into a sweaty mess and freeze when you stop. The benefit of the Atom LT is that it’s one of the thinnest options for insulation and it can perform well as a mid-layer.

The design of the hood like most hooded Arc’teryx jackets is spot on, it has enough room for helmets or hats or whatever you choose to put on your head. Even without a helmet or hat on the hood is adjustable and quite comfortable to use as it tightens around the back, sides and top of the head. The hood performs great in the wind, we’ve had a few windy days here and unlike some of my other hooded clothing items, the Arc’teryx hood stays firmly in place. Like the rest of the jacket, except the fleece panels, the hood has the Coreloft insulation to help keep your head warm.

Other nice aspects of the design include the hand pockets, which are microfleece-lined and roomy enough for gloved hands, not that I needed gloves during this review but I did test it out at home, the drawbacks of testing in the warmer months. The microfleece lining had a very warm feel to it and the pockets are placed well for comfort when you want to warm your fingers.

If you’ve found previous Arc’teryx jackets on the short side, the newer versions have increased their length slightly front and back so you don’t get the dreaded gap on your lower back when reaching or moving around. The Atom LT is roughly 2.5cm longer than previous versions which doesn’t sound like much but should be enough to keep the lower backs of taller people covered. I’m 181cm (5’11”) and have had no problems with the older or newer jackets, but I have heard of taller folk complaining of the shortness of the jackets. The Arc’teryx Atom LT is an athletic fit but does have a little room in the middle section if you’re not as athletic as you once were.

Functionality & Ease of Use (Rating: 70%)

The Atom LT is one of the thinnest jackets on the market and excels at functioning as an insulation layer when you are active. Even though it’s incredibly thin, it still weighs in at around 400g, which is a touch heavier than other similar offerings from other companies such as Patagonia and Rab. One drawback with this jacket, and a few others in the Arc’teryx line up, is that it doesn’t stuff into its own pocket and is a little more difficult than other items to compress. If space isn’t an issue, this doesn’t count for much but if you’re trying to save space in a small backpack the lack of this option makes it a bit more difficult to pack compared to other synthetic insulated layers on the market.

The outside of the Arc’teryx Atom LT is coated in a DWR layer (Durable Water Repellent), which allows water to bead and shed off the jacket without being absorbed. I did happen to wear this jacket in the rain while walking my dogs, not the most outdoors of activities but still, the water beaded well until the jacket was very wet. Despite having soaked the jacket and me, in the rain, it still managed to keep me warm while I was walking, which is one of the benefits of the synthetic insulation used in the Atom LT. Like all DWR layers, it will wear off over time. It can be reapplied but, in my experience, it’s never quite the same as when new, although, I haven’t had this jacket long enough to see if this experience will hold true on the Atom LT as well. Although providing incredible breathability the fleece panels are quite water-absorbent even with the DWR coating, a drawback of having a really breathable jacket.

I’d generally wear this jacket in the dry or paired with a hard shell for rain, snow or super windy days in the cold. The breathability of the side panels means you won’t be as sweaty as when wearing other insulating layers but it does make the jacket loses a bit of its ability to resist wind. You will feel the wind through this jacket on very windy days.

The Arc’teryx Atom LT has 3 pockets, two mentioned earlier, for your hands and a third zippered chest pocket. The hand pockets will probably be blocked by a harness, either climbing or backpack style harness which is a little irritating, but the natural positioning makes them a comfortable option when not wearing a harness. The chest pocket is on the left and is roomy enough to fit a mobile phone or similar item.

I really enjoy the excellent mobility in the Arc’teryx jackets and the Atom LT was no different to others I’ve tested, it provides a great range of mobility in the shoulders and neck, with or without the hood on. As the Atom LT is an athletic fit this can feel a bit surprising to have such a great range of motion in a somewhat tight-fitting jacket.

Overall, for an insulating layer in the cold, the Arc’teryx Atom LT is great, like most Arc’teryx clothing lines it’s priced on the higher end of the scale but the fit, mobility and hood make it a great choice when doing activities outdoors in the cold as either a base or mid-layer. It needs to be combined with another layer if it’s going to be windy or if you want more warmth but for most Australian climates and uses it’s a nice warm breathable layer. It’d be difficult to choose from the Proton LT or the Atom LT as I’ve found them very similar but would probably go for the Proton LT for my style of use but both jackets would be a great choice.

What I Like

  • Fit
  • Mobility
  • Thinness
  • Pockets

What I Don’t Like

  • Hard to differentiate between Proton and Atom LT line
  • Packability

Get One

The Atom LT Hoody can be purchased online, directly from Arc’teryx.
Disclaimer: The Arc’teryx Atom LT Hoody was provided for review. This has no influence on the opinions presented above.
Have you tried the Atom LT Hoody? Got any questions or comments? Let us know by commenting below.