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

I'm 5'11", 165 lbs, athletic build. Size M fits me perfectly. 

My size is always the same. Arc'teryx, Patagonia, TNF, Salomon, Columbia, Nike, Adidas, Under Armour, Zara... Doesn't matter. 

• Arc'teryx's 2024 men's fit revision

Straight from arcteryx.com on what's changed: 

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

Not all jackets come with revised fit. Only the ones with following statement. 

• Poll

Which Arc'teryx fit do you prefer?

Legacy fit

Revised fit

• Poll

Which cuff type do you like more?

Stretch gusset cuffs

Stretch knit cuffs

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).