Long-term review: Western Mountaineering AstraLite || Very warm & light

In a one-week period in April I fielded three inquiries about the Western Mountaineering AstraLite, which was released in spring 2018 and which I’ve used for about 30 nights while scouting the Yosemite High Route in August, guiding trips in Sequoia-Kings in September, and enduring cold-and-wet conditions in West Virginia in May. I will use it again in July in the High Sierra, but intentionally I’m not taking it to Alaska this month.

I can’t recall another quilt that garnered such interest, and I attribute that entirely to the manufacturer. Western Mountaineering has been making premium down sleeping bags and insulated clothing since the early-1970’s in San Jose, Calif. And it’s still owned by Gary Schaezlein, who co-founded the brand with Jeff Jones.

Long-term review: Western Mountaineering AstraLite

The AstraLite is the first sleeping quilt from Western Mountaineering. It weighs a sweet 16 ounces (454 grams) and is appropriately rated to 26 degrees (-3 C), making it perhaps the warmest-per-weight quilt on the market. It’d be ideal for:

  • Mountain West: May through mid-October; and,
  • Desert Southwest: Spring, fall, and most of the winter.

I would not recommend it for humid or rainy climates. If you backpack primarily east of the one-hundredth meridian or west of the Cascades, look elsewhere.

As a top quilt, the AstraLite performs wonderfully in a hammock or in a ground system (if you are a calm sleeper, utilize its pad attachment system, and/or use it inside of a bivy sack).

The AstraLite is a premium-grade product: made in the USA, 850-fill humane European goose down, 4.5 inches of loft, 7d and 10d shell and liner fabrics, and an insulated neck yoke — plus top-notch craftsmanship and customer service.

But you’ll pay for it. At $420 MSRP, the AstraLite is universally more expensive than the best offerings from younger direct-to-consumer brands like Enlightened Equipment, Nunatak, Katabatic, and ZPacks.

AstraLite vs NanoLite

The AstraLite was launched simultaneously with the Western Mountaineering NanoLite, which is lighter (11 oz) but less warm (38 degrees). If I were to review the NanoLite specifically, my comments would be mostly the same.

The AstraLite and NanoLite are identical in every way besides loft (which is a function of their respective fill weights and baffle heights). They share the same down quality, shell and liner fabrics, baffle construction, pad attachment system, dimensions, and neck yoke.

If I backpacked primarily in the warmer desert Southwest, I’d probably get more use out of a NanoLite, because it’s comfort range overlaps more with with the prime backpacking months. But in the Mountain West, it’d be suitable only for the warmest summer nights, or for warm sleepers.

The NanoLite is lighter (and less warm) than the AstraLite. In the Mountain West, it’d be a summertime-only product. It’d get more use in the warmer Southwest.


In the summer my sleeping comfort is about 10 colder than the average backpacker. I get scarily thin and I usually cowboy camp, making me more vulnerable to radiant heat loss and nighttime katabatic winds. To push a sleeping bag or quilt to its advertised or EN-tested comfort temperature rating, I expect to sleep in most of my clothing (hiking shirt, shorts and underwear, trekking pants, fleece mid-layer, and hooded down jacket).

Nighttime temperatures in Yosemite in August were in the low- to mid-30’s; in Sequoia-Kings in September, mid- to high-20’s; and in West Virginia in May, low-40’s and wet. I was comfortable on all trips, and concluded that the AstraLite’s 26-degree rating was fair and appropriate.

To remain comfortable on the September trips, when the lows were regularly at the AstraLite’s comfort limit, I swapped the Big Agnes Insulated AXL (my review) for a warmer Therm-a-Rest NeoAir XLite, and I more often used the AstraLite’s draft closure system.

I see little sense in a quilt that is rated for temperatures colder than the high-20’s. Beyond this threshold, high-loft head insulation is absolutely mandatory, and at that point you might as well use a traditionally mummy bag, which is simpler and less vulnerable to drafts.


The AstraLite and NanoLite are both available in two lengths:

  • 5’8″ version for sleepers less than 6’0″ tall; and,
  • 6’4″ version for sleepers between 6’0″ and 6’6″.

With quilts, it can be difficult to make sense of the width spec, which Western lists as, “up to 68 inches.” More helpfully, the AstraLite and NanoLite are based on Western’s Ultralite mummy bag, which has a slimer profile of 59, 51, and 39 inches at the shoulder, hip, and foot, respectively.

Insulated draft yolk

The chief downside of sleeping quilts is their draftiness. Active sleepers have an especially tough time, constantly revealing their non-insulated backsides, or breaking the seal between the quilt edges and the pad. But even calm sleepers like me lose heat around the shoulders and neck.

The AstraLite reduces drafts with a comfortable neck yolk. To employ, snap the two top corners together and tighten the cinch cord that runs through the quilt’s top hemline.

The yolk makes a significant difference in nighttime comfort, especially when temperatures are approaching the quilt’s comfort limit. But it still does not rival the cocoon sensation of a mummy bag or the warmth of the hideaway hood on the (notably heavier) Sierra Designs Nitro Quilt.

The neck yoke reduces drafts by cinching gently around the neck.

Pad attachment system

The AstraLite has three 3/8-inch elasticized grosgrain webbing loops on its underside, through which a sleeping pad can be inserted. This creates a seal between the edges of the quilt and the sleeping pad, making the quilt function more as a true top bag.

The loops are simple and effective, but they are a little fussy. I found it best to slide a partially inflated pad through the loops, adjust as necessary, and then fully inflate the pad.

I removed the uppermost loop, which is a few inches below the top hemline. When this loop is engaged, it feels as if you’re attached to a backboard, which defeats a primary selling point of quilts: their free-form nature.

On the back of the AstraLite, there are three 3/8-inch elastcized grosgrain webbing loops. (I removed one.) A sleeping pad can be inserted into them, to create a tighter seal between the quilt and pad.
Side view of the pad attachment system when engaged.

Moisture resistance

Based on its performance in the High Sierra last year, I was inclined to give the AstraLite a hearty thumbs-up. It offers a lot of warmth for just 16 ounces. But after using it for two 3-day cold-and-wet trips in West Virginia, my endorsement is now qualified.

I don’t know the exact cause, but the AstraLite (and presumably the NanoLite, too) floundered in consistently wet conditions. My quilt never came into direct contact with moisture (e.g. splatter, a dunking), but it was wetter than other bags: clients observed it during a mid-day “reset dry,” and it was very evident to me after the trips when I was drying my quilt and their demo bags.

As a result of it absorbing ambient humidity, the AstraLite was far less warm, performing more like the NanoLite than a dry AstraLite. This issue had presented itself slightly on my earlier trips, but in the semi-arid Mountain West it was much less noticeable.

The list of potential explanations is short. Either the down (which is not treated to be more water-resistant) has poor resistance to moisture, or the fabric breathability is low. Either way, this is a lovely product for semi-arid and arid climates, but not a great option for humid ones.

Especially in the footbox, the AstraLite performed poorly in consistently wet conditions. The bag was not exposed directly to moisture, but simply absorbed ambient humidity.


Sleeping quilts cannot be EN tested. And without this apples-to-apples rating, we’re unable to definitively answer the fundamental question when purchasing a sleeping bag or quilt, “What is the most thermally efficient bag with my required price point, dimensions, materials and construction, and company values?

Products specs can shed some insight, but it requires a deep dive into the details (e.g. loft, fill weight, length and width), none of which are independently verified and/or held to an industry standard.

The good news is that buyers have more choices — in both the number of brands and the number of excellent products — than ever before. If you do a little bit of homework (e.g. online reviews, and ideally in-person inspection), you’re almost guaranteed to be happy with your purchase.

Buy now: Western Mountaineering Astralite

Have questions about the AstraLite or NanoLite, or an experience with it? Leave a comment.

Disclosure. I strive to offer field-tested information, insights, and advice, and I have a long-term incentive to be a trustworthy source. I do not publish sponsored content or native advertising, and I do not accept payments in exchange for reviews. I have no financial affiliations with or interests in any brands or products.

This website is supported by affiliate marketing, whereby in exchange for referral traffic I receive a small commission from select vendors like REI or Amazon, at no cost to the reader. This post contains affiliate links.

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