Arc’teryx Nuclei SV Review: Warmest Arc’teryx synthetic

I own all Arc'teryx synthetics. Everything from Proton, Atom and Nuclei (all Winter 2024 versions).

Nuclei SV (Men's - Women's) is the warmest Arc'teryx synthetic.

Also see this Best Synthetic Insulated Jackets guide: https://outdoorcrunch.com/synthetic-insulated-jackets/

As long as your expectations and intended use are in the right place, it's honestly literally impossible to be disappointed with this stunning jacket in my opinion. 

The fact that this item is extremely high quality is evident all the time. 

Even just taking a peek at the random photos I laid out at the bottom of this post can make you understand. 

Overview

Nuclei SV is actually a belay jacket. Meaning that it's primarily meant to maintain your core temp when you stop moving. 

But I use it casually as well. All the time. I wear it as if it's a down jacket that can get wet. 

I, however, of course make sure that my output will be none to low. Otherwise I sweat like a pig inside this jacket. Just like I do in down jackets. 

Because the breathability of Nuclei SV is absolutely horrible. I don't even take uphill hikes or power walks with it. I'm one of those people who feels super uncomfortable with feeling "clammy". So I'm always prepared beforehand. 

But this isn't "bad news". Because Nuclei SV isn't meant for this anyway. Actually, this is even an advantage if you ask me. 

Because, when the air permeability is so low, when you put it on you feel warm at such an instant that it's insane. You need to try it out to see it for yourself. 

• Fit

Canberk is 5'11" and 165 pounds, with an athletic build. Size Medium fits him perfectly across almost all brands and product lines. 

• Arc'teryx's 2024 men's fit revision

Here's what Arc'teryx says about its most recent fit revision: 

Source: https://arcteryx.com/us/en/help/sizing/mens/tops/new

Not all jackets come with the revised fit - only the ones with following statement: 

190 + 90 gsm of synthetic fill is very generous to say the least. Besides zero air permeability, this is another reason why it's the warmest Arc'teryx synthetic. 

Arato 15 face fabric is smooth to touch and makes the inner fabric is pretty comfortable to contact with the skin, although it's extremely fragile and hence not suitable for things like climbing at all. 

Don't even THINK about not being gentle to this item. 

3 external (1 chest + 2 hand warmers) and 2 internal drop-in pockets are roomy and offer plenty of storage options. 

Nuclei SV also offers a two way zipper (rarely seen in Arc'teryx jackets), which offers added breathability and comfort - especially when wearing a longer jacket like Nuclei SV. 

All in all, if your expectations are in the right place, it's literally impossible to be disappointed with this stunning jacket in my opinion. 

Arc'teryx shines the most when it comes to synthetic insulated jackets. For down jackets, it still outperforms other brands like Rab and Mountain Equipment. But the difference there is less than the difference in synthetics. 

Synthetics from other lines, like the Atom and Proton lines (read how those to compare in here) are all fantastic and you probably have never heard any bad things about any of them. Overwhelming majority of users are extremely happy with them. 

Some synthetics like Dually Belay and Fission SV are discontinued over time. 

Nuclei line (FL (now "base") and SV) too was one of them once but Arc'teryx had recently brought them both back to life. 

I immediately grabbed both. 

Warmth

Front, back and upper arms are all equipped with ample Coreloft Continuous at 190 gsm. In addition to that, the sides, hood, lower arms and underarms are reinforced with 90 gsm of it. 

A single layer of 90g/m2 at underarms, lower arms, sides, and hood. And two layers for a total of 190g/m2 everywhere else (front, back, upper arms). 

Weather Resistance

Blocks the wind like it's nothing. 

It does come with DWR coating. 

Durability

Outer fabric is tear prone. Extremely fragile. 

Two way zipper

Lengthy design of Nuclei SV adds to its warmth as it covers your butt more than shorter jackets. Still, with a lengthier jacket, comfort is what you sacrifice a little bit in return.

This is because the jackets get crumpled when sitting down. It can be especially uncomfortable when driving or cycling. 

Arc'teryx sidetracks this problem by adding a two way zipper. It basically allows you to keep the upper half of the jacket zipped while keeping the bottom half unzipped. As a result, the jacket doesn't get crumpled anymore as you legs don't get in the way. 

Most Arc'teryx users usually complain about Arc'teryx not having enough amount of jackets with a two way zipper. This puts the Nuclei SV even more in front compared to the other models. 

Other benefit of a two way zip is that it allows for mechanical venting. Mechanical venting is the most important component when it comes to the ultimate breathability of a jacket.

Mechanical venting is achieved either by pit zips or a two way zipper. A toasty jacket like Nuclei SV definitely has the potential to overheat most of us even when using it for low output activities (e.g walking). 

So it's amazing to have an option like this - especially if you have a special desire about not sweating but at the same time you wouldn't want to get cold either. 

In other words, it allows fine tuning for the warmth level. 

Packed size

As you can guess, Nuclei SV isn't packed that small. 

Nuclei SV packed size: 11 in (or 28 cm) length x 7.1 in (or 18 cm) diameter. 

Nuclei SV is packed into the stuff sack that comes attached to one of the dump pockets: 

I prefer packing into attached stuff sacks to packing into pockets any day. The drawcords make packing much easier. 

Pockets

Pocket sizes:

• Hand warmers: 11.8 in (or 30 cm) x 7.5 in (or 19 cm)
• External zippered chest pocket: 11 in (or 28 cm) x 8.3 in (or 21 cm)
• Dump pockets: 7.5 in (or 19 cm) x 10.2 in (or 26 cm)

Cuffs

Cuffs are elastic and in my opinion well constructed. I like Arc'teryx cuffs a lot, but those of like Atom SL, for example, are a bit too loose. I feel the same for Patagonia's Nano Air (2024) as well. 

Nuclei SV is just right. 

Alternatives?

No alternative in Arc'teryx line up at this warmth level. Maybe take a look at Patagonia's DAS. 

More photos of Nuclei SV

Find more photos below.