The Arc’teryx Atom Lt Hoody Men’s & Women’s is one of those garments that you will find yourself making excuses to wear, even when it’s not quite appropriate. The good news is that this is a pretty darn versatile jacket, so excuses are often not required. Arc’teryx describe the Atom Lt as an active-use insulation layer, providing vital core warmth with liberal mobility and breathability. I’d be hard pressed to give a more accurate description in 10 words or less, but there is also lot more to this jacket than one might realise at first. It’s been a modern classic among outdoor enthusiasts for a while now & when an opportunity came to get into an Atom Lt Hoody a couple of months ago, I was incredibly keen to sign up.

Design & Specs

Essentially the Atom Lt Hoody is a synthetic based insulation piece that can serve as both a mid-layer or Outer layer depending on the weather & your clothing system. This a lightweight jacket (approx 360g) so even light enough to consider taking when there is just a chance you’ll need it. The main body & arms of the jacket use synthetic insulation called Coreloft, which is essentially the proprietary Arc’teryx equivalent to the more widely known Primaloft. The rating or ‘weight’ of the Coreloft is 60 g/m² & it’s made from a highly crimped polyester yarn that both compresses well & retains it’s loft. The Stretch side panels found down the side of the torso (under your arms) are Polartech Power Stretch with Hard-face technology, so warm highly stretchy fleece that also breathes very well. These panels serve to reduce the dreaded underarm bulk found in some warm jackets, plus they allow heat to vent when you’re working hard. The outer shell  is a  nylon taffeta fabric called Tyono, which super light & has a soft hand. But don’t let that fool you into thinking this is a weakling of a jacket, it’s also DWR treated & quite durable. The Atom Lt is not a wind/waterproof jacket, but it’s quite wind & moisture resistant. Like most synthetic based insulated pieces it’s perfect for both dry & moist conditions.

The fit is athletic, in the Arc’teryx sizing range it’s a Trim Fit. So it’s close fitting but roomy enough for a base-layer & low-bulk mid layer underneath. I found I could wear an Icebreaker 200gsm base layer, plus a 100 weight fleece under the my large Atom Lt, with a touch of room to spare (but I’m pretty skinny!). There is a elastic hem cinch & it’s slightly longer at the back to give you more ‘bum coverage’. The soft hand-warmer pockets sit high & don’t interfere with a climbing harness or pack hip belt. The sleeve cuffs are elasticated perfectly, snug enough to stop drafts but they expand so you can slide the sleeve us your forearm comfortably. The hood is simple but well considered, it’ll go over a helmet, but can also cinch down using the elastic pull adjustment at the back for use without a helmet.  There is no built in stuff sack, but the jacket rolls easily into the hood & will stay quite compressed. Beyond that, The Atom Lt. just simple and pared down, classic Arc’teryx: functional & comfortable.

Atom Lt Dyp home

A study in Versatility

For me, adventure trips often involve a variety of activities & vast changes in weather. Finding clothing that will excel throughout the different needs & situations of this kind of journey is key. Especially when keeping pack size & weight to a minimum is a priority. When choosing what to pack, I’ll look for gear that serves multiple duties, but also isn’t a compromise. Sure that’s a lot to ask, but modern clothing technology is pretty amazing & garments like the Atom Lt can pack a lot of varied usability into one tidy package.

Coming from a QLD summer, I was very excited to get into the Atom Lt upon arriving in Queenstown this last February. I’d even rolled the Atom into it’s hood & used it as a pillow on the plane, hoping to deploy it upon landing! The weather was sadly unseasonably warm when I arrived, but gladly it cooled considerably in late evening. Thus begun my love affair with the Atom Lt. The next morning we were strolling along the lakeside together as the sun rose majestically above the mountains… OK OK, I’ll keep it on track. In all seriousness I was impressed right from the start at the range of temperatures I could wear the Atom in, from cool windy evenings hovering around 15°C, to temps well below freezing later in the trip. The styling is understated, so I never felt out of place wearing the Atom around town, be it meeting a friend for dinner at a nice Queenstown restaurant, or stopping by the pub before (& after & before again) forays into the mountains.


Early morning overlooking Lake Wakatipu, Queenstown.

Mountain testing

The real test though, was how does it perform in harsh conditions. The New Zealand Southern Alps are renowned for wild & wet weather, any time of the year. Luckily for the first half of the trip, when I was doing some alpine climbing, the weather was fairly mild. I used the Atom a lot, around camp & even whilst sleeping in open bivouacs. The warm hood was great to sleep in when the temps below Mt. Brewster dipped below freezing overnight. Whilst climbing I was impressed how well the Atom Lt. vented heat, but also kept me warm when stationary. Often I found myself just wearing the Atom over a long sleeve merino base-layer. There was only a few times when I felt the need to cover the Atom Lt with my hard-shell jacket, such as the summit traverse on Mount Brewster & the subsequent wet, cold & prolonged rappels afterwards. Most of the time, the Atom alone whilst climbing was fine, it cut the wind & kept my body temperature well regulated.

Atom Lt Dyp brewster

L: Waiting in a crevasse whilst descending off Mount Brewster, the Atom Lt under my Theta AR Gore-Tex. R: Waking up at our bivvy below Mt. Brewster, there was ice on the bivvy sack so it was below freezing overnight.

Later in the trip, I walked through the Mount Aspiring National Park for a week, encountering 5 solid days of torrential rain, sleet, wind & snow. The temps never dropped too far below freezing, so I was able to get by wearing my base-layer, a light fleece & shell jacket whilst walking. The Atom Lt was my saving grace, kept tucked away safely in a dry-sack in my rucksack. Always it was ready to bring my body temperature back into the happy place at the end of some hard, wet cold & long days. That said, knowing I could use it if required in the wet conditions was always an option, as the synthetic insulation would retain the vast majority of it’s thermal efficiency even when wet.

AtomLT Dyp

L: Venturing out once the rain began to ease, Dart Hut in the Background. R: Waiting out wet weather in Dart Hut

Initial Conclusions

If you haven’t guessed it already, I love this jacket. It served me very well in NZ & I’ve already had a chance to use it a couple more times here in QLD on some overnight climbing trips. My only gripe is that it’s too hot here in Brisbane to wear it most of the year, but that’s not really the Atom’s fault. If you’re looking for a light insulation piece that will fit into a huge range of adventures, definitely consider the Atom Lt. Hoody. Be warned however, once you try it on you’ll want one. Trust me.


Looking up at Aoraki/Mount Cook, after Sunset with the soft pink alpenglow illuminating the landscape.

REVIEW: Arc'teryx Atom Lt Hoody
Warmth to Weight90%
Weight & Compressability85%
Comfort & Fit99%
Weather Resistance80%
  • Warm for the weight
  • Super versatile, can be used for so many applications.
  • Simple functional & timeless design
  • Not as warm/compact as a down eqivalant for the weight
  • Too good looking? I'm stuck to find any other downfalls!
90%Overall Score

About The Author

Lachlan Gardiner

Lachlan works as a freelance photographer, writer and videographer. He loves spending time in the outdoors whenever possible - be it hiking, mountaineering, climbing, or just being on the road - He'll take any excuse to get into the mountains! He also works in our Paddy Pallin store in Fortitude valley, Brisbane. Drop in and say hi!

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