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Arc'teryx Nuclei FL Review

When it comes to features, this jacket has everything you need and nothing you don't
Arc'teryx Nuclei FL
Photo: Backcountry
Editors' Choice Award
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Price:  $300 List | $299.00 at Backcountry
Pros:  Light, easily stowable, very weather resistant
Cons:  Doesn't breathe, expensive
Manufacturer:   Arc'teryx
By Matt Bento ⋅ Senior Review Editor  ⋅  May 12, 2021
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74
OVERALL
SCORE


RANKED
#1 of 13
  • Warmth - 25% 8
  • Weight and Compressibility - 20% 8
  • Comfort - 20% 7
  • Weather Resistance - 20% 8
  • Breathability - 15% 5

Our Verdict

Somehow, the Arc'teryx Nuclei FL manages to tick every box on our insulated jacket wish list, making it our favorite design to balance warmth, weight, and features. It wins our highest award, and we believe that it's the best midweight model for backcountry recreation (if you can afford it). The Nuclei is windproof, water-resistant, and highly packable and is one of the lightest models we tested. Unless you're looking for the absolute warmest in synthetic insulation, the Nuclei is the way to go.

Compare to Similar Products

 
Arc'teryx Nuclei FL
Awards Editors' Choice Award Editors' Choice Award  Best Buy Award Top Pick Award 
Price $299.00 at Backcountry$329.00 at Backcountry$299.00 at Backcountry
Compare at 2 sellers
$194.95 at Backcountry
Compare at 2 sellers
$299 List
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Pros Light, easily stowable, very weather resistantLightweight, wind and water resistant, quite warm, durable face fabricWarm, good water resistance, comfortable, excellent mobility, stylish, durableLightweight, warm, great wind protection, sheds water well, affordableVery warm, comfortable fit, seals out the weather
Cons Doesn't breathe, expensiveExpensive, no hem drawcords, hood is slightly tight with a helmet onExpensive, annoying hem cinching buckles, not the lightestDoesn’t breathe well, fit isn’t very athleticHeavier than most, not very breathable, pricey
Bottom Line When it comes to features, this jacket has everything you need and nothing you don'tA versatile and lightweight insulated jacket that offers superior weather resistance, and remains impressively warmThe top overall performer among the active insulating jacketsThe best lightweight insulated outer layer is highly wind resistant and impressively warmA very warm, weather resistant hoody that easily fits over other layers but isn’t too baggy
Rating Categories Arc'teryx Nuclei FL Patagonia DAS Light Hoody Arc'teryx Proton LT Hoody Rab Xenon Hoodie Arc'teryx Atom AR Hoody
Warmth (25%)
8
8
6
7
9
Weight And Compressibility (20%)
8
8
7
8
4
Comfort (20%)
7
6
9
6
9
Weather Resistance (20%)
8
8
6
8
7
Breathability (15%)
5
5
7
5
4
Specs Arc'teryx Nuclei FL Patagonia DAS... Arc'teryx Proton... Rab Xenon Hoodie Arc'teryx Atom AR...
Measured Weight (size) 10.5 oz (S) 11.0 oz (S) 12.8 oz (S) 11.0 oz (S) 15.2 oz (S)
Insulation Coreloft (65g/m²) 65 g PlumaFill 100% recycled polyester Coreloft Compact 80 60 g Stratus 120 g/m2 Coreloft body, 80 g/m2 underarms, 60 g/m2 hood - with Dope Permair 20 in armpits
Outer Fabric Arato (10D nylon ripstop) 10-D 100% nylon ripstop Pertex Endurance Fortius Air 20 Atmos ripstop Tyono 30 denier nylon
Stuffs Into Itself? Yes Yes Yes, clip loop Yes, clip loop No
Hood Option? Yes Yes Yes Yes Yes
Number of Pockets 2 zippered hand, 2 internal 1 chest zippered, 2 handwarmer zippered 2 insulated zippered hand, 1 zippered chest 2 zippered hand, 1 zippered internal chest 2 zippered hand, 1 zippered internal chest

Our Analysis and Test Results

Arc'teryx has been cranking out high-quality insulated puffys for decades, but the Nuclei FL is the first one we've encountered that perfectly fits the needs of the summertime alpine climber or any climber who is up high, belaying as the shadows start to fall. The Nuclei is similar to several past award winners and has many of the same features, but it functions better than its competition, making it our favorite insulated jacket for climbing or as a midweight layer for hiking and camping.

This model manages to add more insulation, puff if you will, without making it heavier than its closest competitors. In terms of warmth-to-weight ratio, it's a masterpiece that has everything we look for in an "on route" puffy — without the fluff. It stuffs into a small included stuff sack, not its own pocket, and even this simple feature is an improvement on traditional designs.

Performance Comparison


This jacket has no issues with a morning of bushwhacking and...
This jacket has no issues with a morning of bushwhacking and scrambling, but it's more suited to stationary activities like belaying.
Photo: Jason Peters

Warmth


The Nuclei's 65 grams of Coreloft seems to be the sweet spot for keeping the weight low while providing plenty of insulation. Unlike some other popular insulated jackets from Arcteryx, the Nuclei doesn't have any stretchy panels for venting or increased range of motion, just uniform insulation under the arms, across the shoulders and back, and everywhere else, including the hood. Other warmth-inducing features include cinch cords at the hem and on the back of the hood, and elastic on the wrists.


We found this puff more than adequate when placed over a midlayer on days at the crag where temps never climbed past the low fifties in the shade. On route, it's perfect to pull out as soon as you reach a belay to seal in all the heat you built up while climbing. We also pulled this jacket out on windy summits and ridges during some spring ski touring. It kept the wind at bay while we took photos and waited for our splitboarding friends during transitions.

The Nuclei has an incredible amount of loft, especially considering...
The Nuclei has an incredible amount of loft, especially considering its light weight.
Photo: Jason Peters

Weight and Compressibility


On our scale, the men's small Nuclei weighs in at 10.5 ounces.


It's not the lightest insulated jacket in our review, but it's within two ounces of the lightest and still provides plenty of warmth. Unlike the Arc'teryx Atom LT or the Proton, the Nuclei includes a stuff sack.

While not the lightest jacket in our selection, it's still...
While not the lightest jacket in our selection, it's still featherweight and is warmer than its lighter competitors.
Photo: Matt Bento

This stuff sack is permanently fixed to the inside of the jacket and sits conveniently inside the right side drop-in pocket. This stuff sack is roomier than most of the pockets on competing models stuff pockets, making putting the Nuclei away or taking it out at belays much easier. We found it very easy to clip the stuff sack to the anchor and pull the jacket out without any fear of dropping it, and could easily reverse the process to stow it away. You won't get pumped stuffing this jacket away, and you're less likely to drop it while pulling it out, so you won't hesitate to put it on, even if you're just a little cold. The result is that you'll stay more comfortable on route, looser, more relaxed, and primed to send when you leave the belay.

We're big fans of the convenient stuff sack that actually fits the...
We're big fans of the convenient stuff sack that actually fits the jacket.
Photo: Matt Bento

Comfort


Though not as comfy as a soft, breathable jacket, the Nuclei feels nice against the skin, and its Arato 10D ripstop shell fabric doesn't feel like a crinkly garbage bag. In the past, a few of our testers have lamented that Arc'teryx jackets fit a bit short at the hem. The Nuclei felt about perfect under or over a climbing harness, and it tapers down in the back for extra bum warmth.


A size small fit our 5'9" 150 pound lead tester perfectly. It doesn't restrict movement and is still large enough to fit over a fleece and lightweight jacket. The hood features a drawstring to keep it in place over your bare noggin, and it's large enough to fit over a climbing helmet.

Arc'teryx didn't skimp on the full-size, super comfy handwarmer...
Arc'teryx didn't skimp on the full-size, super comfy handwarmer pockets.
Photo: Jason Peters

Two zippered handwarmer pockets are ample enough for a few bars, a topo, and a headlamp, and there are two internal drop-in pockets to keep gloves or even climbing shoes warm. This jacket doesn't have a chest pocket, but we can't say we really missed it all that much. If there is one thing we'd add, it'd be a two-way zipper to help keep the jacket out of the way of our belay loop.

The chest pocket is handy for phones, lighters, topos, headlamps...
The chest pocket is handy for phones, lighters, topos, headlamps, batteries, pens, paper, energy gels, or anything else you need to access quickly.
Photo: Jason Peters

Weather Resistance


The Nuclei keeps the wind out with Arc'teryx's proprietary Arato shell fabric.


This ten denier ripstop nylon isn't completely waterproof, but it does an admirable job at keeping us dry in snow and light drizzle and even did well in a simulated downpour. After two months of testing, the DWR coating is holding strong and still causing water to bead off the jacket instead of wetting out the shell fabric.

The hood has an excellent fit and keeps your head and neck cozy on...
The hood has an excellent fit and keeps your head and neck cozy on windy days.
Photo: Jason Peters

Breathability


This compact puff keeps your body heat close and keeps the weather out, allowing little permeability for breathing.


Moving quickly on approaches, we could barely go a mile without needing to stop and take it off before getting uncomfortably sweaty, but that's how you know it's working! At least the synthetic Coreloft insulation won't lose its loft if you happen to saturate it with your perspiration. In all seriousness, athletes on the move will need a more breathable layer if they want a jacket they can leave on, while the Nuclei keeps you warm once you've stopped moving.

When the shade hit, we loved the instant feeling of warmth we got...
When the shade hit, we loved the instant feeling of warmth we got from pulling this jacket on.
Photo: Matt Bento

Value


This jacket is priced similarly to its closest competitors from Patagonia, and its quality and refined design are on par with other excellent products we've tested from Arc'teryx. If the price is too steep, it's worth checking out other models, like the Rab Xenon, which is very close to matching the Nuclei in performance but retails for nearly half the price.

Conclusion


The competition is stiff, but the Arc'teryx Nuclei ekes out a win. You can't go wrong bringing this model with you for multi-pitch climbing, spring ski touring, camping, or even as a warm layer to throw on before you run errands around town. In terms of a puffy to bring for climbing long routes, the Nuclei is as near to perfection as we've seen.

While this jacket isn't constructed from stretchy fabrics, it fits...
While this jacket isn't constructed from stretchy fabrics, it fits in a way that doesn't restrict mobility.
Photo: Matt Bento

Matt Bento