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. The NanoLite retails for $345.

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 yoke

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 yoke. To employ, snap the two top corners together and tighten the cinch cord that runs through the quilt’s top hemline.

The yoke 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.

Due to low fabric breathability, the AstraLite flounders in wet conditions. The same will be true of the NanoLite. My quilt never came into direct contact with moisture (e.g. splatter, a dunking), but it retained more moisture 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.

Both quilts use the same 7d shell fabric, which was given an acylic “kiss coating” to increase the strength of this otherwise delicate material. But Western Mountaineering admitted to me in an email that this roll-liquid coating also “reduces the breathability substantially.” The WM rep shared that they could “literally see the water droplets condensed on the inside of the shell through the fabric” during recent use.

As a result of its poor breathability, the AstraLite’s down was compromised by moisture and became 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.

Other AstraLite owners have made this same observation. Refer to comments below by John Vance and H. Hall.

Until the shell fabric breathability is addressed, the NanoLite and AstraLite are lovely products for semi-arid and arid climates, but not a great option for humid ones.

Update, July 2020

Per WM:

“It’s a frustrating situation because the fabric we received from our manufacturer was effectively not the fabric we had developed with them leading up to that, but I would say that we blew it by not taking the time to confirm its performance.”

WM has replaced the original fabric of the Astralite “with a grey 12D Nylon Ripstop (same fabric as the EverLite) and the Nanolite is using a sky blue 12D Nylon Ripstop (looks nearly identical just less translucent). The 5’8” astralite weighs in at 1lb 2oz (506g), and the 5’8” nanolite weighs 13oz (370g).”

Additionally, WM is offering to replace the shells as a warranty service. Contact them for details.

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 and trustworthy information, insights, and advice. I have no financial affiliations with or interests in any brands or products, and I do not publish sponsored content

This website is supported by affiliate marketing, whereby for referral traffic I receive a small commission from select vendors like Amazon or REI, at no cost to the reader. As an Amazon Associate I earn from qualifying purchases.


  1. Chip on June 13, 2019 at 2:10 pm

    What would you recommend or central united states?

    • Andrew Skurka on June 13, 2019 at 2:35 pm

      Define central. I think the key thing is that you’re not often camping in the clouds or getting days of rain and overcast, as you do in the Appalachians. You might be able to get away with it around the Great Lakes, which are drier and lower, and then definitely in the plains.

      • Chip on June 14, 2019 at 6:42 pm

        Arkansas, Tennessee, Missouri Eastern Oklahoma.

  2. Iván on June 13, 2019 at 3:01 pm

    What quilts would you recommend for a humid climate? Maybe a synthetic?

    Thank you for your insights!

  3. John on June 13, 2019 at 5:37 pm

    Do you think the wet weather performance was specific to this quilt, or a function of the down insulation generally? (Says the guy who lives in the PNW and is eyeing the REI Magma 30)… Thanks!

    • Andrew Skurka on June 13, 2019 at 6:42 pm

      All my demo quilts and bags are down (Sierra Designs) and they did much better than mine. Not sure if the shell fabrics are more breathable or if the water-resistant down was the difference. I doubt it was user error.

    • Andrew Skurka on June 14, 2019 at 2:33 am

      We had a lot of down bags and quilts on the trip. I don’t think anyone had synthetic, actually. And I was the only one who experienced problems. When my group did a mid-day reset dry, no other bag was as wet looking. And when I was drying out demo gear afterwards, no bag felt as wet as mine. The other down stuff had held up pretty well.

      Point is, I think this WM quilt seems especially vulnerable to moisture, and is not representative of other down products (including other WM products).

  4. Chad on June 14, 2019 at 8:08 am

    Hi Andrew,

    What is your experience when quilts with similar temperature ratings have drastically different fill weights? Notably I’ve consistently read that Western Mountaineering and Katabatic have very trustworthy temperature ratings yet with the “Astralite comparison” they have the lowest fill weights. I notice they also have a greater baffle height than the EE 30 which has more fill. I have been looking at the Nemo Siren due to availability and struggle to compare it to quilts on your list.

    • Andrew Skurka on June 14, 2019 at 9:50 am

      Apples-to-apples comparisons are really hard with quilts. That’s why the EN test is so wonderful — it scientifically demonstrates the thermal efficiency of each bag, per weight.

      With quilts there are so many variables to look at, and it’s difficult to know exactly how they are measuring each spec.

      • Steffen on June 15, 2019 at 7:37 am

        Maybe you quilt needs a gentle (hand) wash: through use dirt and body oils might have build up on both its fabrics and its down. If so, fabrics and down will attract water and condensation can easily transfer into the down.

        If you think your quilt has been extensively used, you could even consider to additionally re-proof it with an aftermarket DWR (e.g. Nikwax Down Proof).

        Less likely, your quilt’s down could have had too much of its natural fat and oil removed by WM’s down supplier, as “a certain amount of lipids are required for down and feathers to be resilient. Lipids on down and feathers help them resist water and also protect them.” (IDFL).

        • Andrew Skurka on June 15, 2019 at 11:47 pm

          The bag has been used for 30 nights, shouldn’t be a wear issue.

          And WM is a down pro, work directly with their farm. Unlikely that they screwed up the supply chain.

  5. Denver_Hiker on June 14, 2019 at 10:51 pm

    I got a wide quilt and am quite skinny. Am I missing some of the warming power of my quilt?
    It is Katabatic’s Wide version. I had originally thought since I toss and turn at night it would make sense but am having second thoughts.

  6. Hunter Hall on June 16, 2019 at 5:02 pm

    I’m taking the nanolite into the Yosemite high country July 1-7. I will report back. I expect it to be perfect.

    For three season use, I have the Z-Packs classic 20° Quilt/bag (with zipper) which honestly I’ve typically found to be a bit overkill for me, especially when wearing a jacket, etc.

  7. Dick Anderson on June 17, 2019 at 2:48 pm

    Yoke, not yolk. Sorry-I’m anal about proper spelling.

    • Andrew Skurka on July 1, 2019 at 10:04 pm

      Thank you. You’re always welcome to correct me — I get it as perfect as I can, but not always perfect.

  8. stephane on June 19, 2019 at 7:41 pm

    I own a WM apache and my wife owns a WM ultralight. Given the ”right” temperature, I systematically wake up with a wetter bag than my wife (and everybody else in the group). That is the reason I bought a synthetic quilt. I still wake up more damp than other with my quilt.

  9. Shae on July 30, 2019 at 9:28 pm

    Andrew, I just want some clarification. If you are sleeping in temperatures below 20F you go with a mummy bag? I’ve seen a lot of different views of cold weather camping and it’s getting me curious. Would one benefit more from getting a mummy bag (western mountaineering lynx) as opposed to a cold weather wuilt(Katabatic grenadier 5 degree) for mild winter conditions here in Colorado? Just want to here a experienced individuals point of view. Thank you sir

    • Andrew Skurka on July 31, 2019 at 6:31 pm

      As soon as temps are mostly below freezing, I go with a mummy. A quilt rated to, say, 5 degrees is stupid, IMHO. Its draftiness has huge consequences, and you need so much extra head insulation that there’s a huge fuss factor, and probably very little weight savings.

      As another CO guy, I find the two-bag combination of a 3-season quilt (that’s still light enough for peak summer temps) and a 10’s mummy (that’s ideal for late-fall and late-winter/early-spring, and okay in mild mid-winter temps) is about perfect.

      • Shae on July 31, 2019 at 8:28 pm

        Thanks so much Andrew. I’m a huge fan so I appreciate you taking the time to respond!

      • Steven on May 29, 2020 at 4:49 am

        Can you give an example of a 3-season’s quilt?

  10. H. Hall on August 7, 2019 at 4:45 pm

    I just got out of the High Sierra with the Nanolight and I had the exact same experience regarding the moisture. I actually took pictures where you can see droplets of water inside the quilt. The only source of moisture was me but I was sleeping under a tarp with a ground sheet and excellent ventilation so I’m a bit concerned/confused about it.

  11. Kody Aigner on September 4, 2019 at 8:59 am

    What are your thoughts on running a half quilt like the Nunatak 40 degree Nano Half Quilt with a high loft down hoodie? I see that this is popular among climbers but I see little mention of this idea among the ultralight crowd. Seems like it could be ideal for more restless but warmer sleepers during summer conditions in the mountain west, also perhaps allowing one to leave their mid layer at home.

    • Andrew Skurka on September 4, 2019 at 8:01 pm

      Never tried this.

      My hunch is that the weight benefit is negligible, because jackets are relatively inefficient insulators versus sleeping bags and quilts. It turns out that insulating rod-shaped objects like arms takes quite a bit of fabric given the volume of body being insulated.

      I suppose it’s more a matter of whether you think your insulated parka needs to be that warm when it’s used only as a parka. I’m not sure what the rationale is for climbers, maybe it’s because they tend to spend a lot of time on belay, generating no heat and therefore need to be very well insulated even when not in their sleeping bag. It’s the opposite for hikers — we move all day and can rely on body heat to stay warm, until we stop, and then we jump into our bag.

  12. John Vance on September 9, 2019 at 11:50 am

    I just returned from a 12 day trip in the Winds with the Astralite quilt and experienced similar moisture build up in the foot box. This was all internal moisture as the outer shell was not exposed to any moisture. I found that turning the quilt inside out was key to helping dry things out but I think that the “acrylic kiss coating” has greatly reduced the air permeability of the exterior shell to acquire greater moisture resistance from the outside.

    Oher than using a different shell material, I think if the footbox was shorter it would help mitigate this and make the quilt more comfortable as from the knees down it is fairly snug. I really like how effective the collar yolk worked even without using the neck snap. I also found the size of the quilt to work very well without having to use any straps at all. My hope is that the acrylic coating will degrade with time and I may have the back opening extended to make it more comfortable and limit the moisture build up to the last two baffles.

    • Andrew Skurka on September 10, 2019 at 3:21 pm

      I’m just really glad to hear that my experience with the condensation has been validated by other users. I wouldn’t expect to find design mistakes from a brand like WM, but I increasingly believe that their fabric selection was in error here.

  13. ben on September 13, 2019 at 10:11 am

    to pile on, i’ve used my astralite for ~20 nights, almost entirely in the sierra. it picks up more moisture than any other quilt i’ve used — though i notice it a bit more in the torso than the footbox. otherwise, i find it to be pretty near perfect.

  14. John Vance on September 16, 2019 at 9:29 am

    As I learn more about acrylic coatings, it may have been as much of a decision to go that route for easier handling of the 7d fabric during cutting and sewing as it was to add a bit of extra water resistance. The good news is that acrylic coatings, as a general rule, are not particularly durable. With it being a “kiss” coating – which is applied via a pick up roller and is a lighter coating that a direct to fabric application – I wonder if a couple of good washings might help degrade it and provide better breathability. A fabric sample would be nice to play with but I don’t think that will happen.

  15. Andrew Skurka on October 1, 2019 at 10:03 am

    I received an update from Western Mountaineering about the moisture problems:

    Basically, it’s an issue of the breathability of the fabric and the construction of the quilt.

    First off, the breathability is not stellar compared to our other fabrics. The producer of our fabric gives it what’s called an acrylic “kiss coating”, basically a roll-liquid coating, to increase its strength because they want the fabric to be at a minimum strength before they’ll willingly distribute it. The coating increases the fabric’s strength and even makes it a little more water resistant, but it reduces the breathability substantially. I used a nanolite this weekend and I could literally see the water droplets condensed on the inside of the shell through the fabric.

    Second, the construction doesn’t allow the foot to breath like the rest of the bag. Because the upper portion of the bag is open in the back, and because there is no hood on the bag, the moisture is able to leave through the openings. On the lower portion the bag is a fully enclosed cylinder that pretty effectively traps moisture.

    On the backburner, we’re trying to source a 7D ripstop that breathes better, but we don’t have any expectations of a production date at the moment.

  16. John Vance on October 1, 2019 at 10:11 am

    Just what we deduced. Opening up the back to extend more to the footbox and working to reduce the acrylic coating may be the best way to go. I will have to research something that will compromise the coating and not the down.

  17. Travis on October 28, 2019 at 3:42 pm

    I have the nanolite and have experienced condensation issues in both the Chisos Mountains of Big Bend at the end of March as well as the High Sierra in August. The amount of moisture in the bag was so pronounced that upon exiting the bag on one particularly cold morning on the JMT the bag became crunchy when the moisture inside froze while I was waiting for the sun to make it over the ridge in Lyell Canyon. Water drops were visible through the fabric. I’ve used the bag about a dozen times now and I’d estimate that on at least half the occasions I’ve ended up with moisture in the bag, particularly the footbox. I’ve never used the bag in rainy conditions, but I imagine its performance would suffer even more as you mentioned. Do you think this is potentially a warranty issue since the fabric they used seems to have serious performance issues?

    • Andrew Skurka on October 28, 2019 at 4:20 pm

      It will definitely struggle more in wet environments.

      The warranty question is for WM to answer. Personally, I don’t think its performance is on par with other WM products.

  18. John Vance on October 28, 2019 at 4:29 pm

    I really like everything about these quilts but the shell material really negatively impacts the performance in the field. It’s unfortunate but not sure what the fix could be. Whether they warranty it or not would depend on many things including how many they have produced. It’s more a poor materials choice that doesn’t hold up to the WM standards their other products employ rather than a manufacturing problem. Unless they spec’d a rate of air permeability that the mill didn’t meet, it’s working like it should.

  19. Spit Walker on January 5, 2020 at 4:48 pm

    Another astralite owner here. I have had the same experience. Used it 50 plus nights under a tarp.
    I think I may contact WM and ask about a warranty.

    • Travis on January 8, 2020 at 11:33 am

      I reached out to them via email on 11/1/19 and still haven’t heard any response regarding any warranty issues. I also contacted Backcountry.com (where I purchased) and they told me someone from WM would be contacting me and that they handle claims in the order they are received. Seems odd to me that a brand known for quality with such an impeccable reputation would have a two month wait time on processing warranty claims. Maybe my email slipped through the cracks.

      • Spit Walker on January 8, 2020 at 12:49 pm

        I sent an email January 5 2020.
        Have yet to hear back will post if and when they get back to me.

  20. Steve D. on April 24, 2020 at 11:08 pm

    Would reversing the fabrics help with the condensation if the source of the moisture is from the body.
    I just ordered a NanoLite today and can’t test this theory.

    • Andrew Skurka on April 25, 2020 at 5:49 am

      That might help the breathability issue. but the baffles are constructed such that they naturally wrap around the body. I can’t remember what western mountaineering calls this, maybe differential baffles. The point is that you can’t flip the quilt inside out well still expecting the bag to fit properly.

  21. Spit Walker on April 25, 2020 at 8:58 am

    For what it’s worth WM made me a new quilt with a more breathable shell fabric. They used the same fabric as the versalite bag. So slightly heavier fabric but hopefully a better overall quilt now. They also upgraded the strap system on the quilt as well which is way more simple and effective. This exchange process was about 2 months long. I expect this quilt to perform as well as any quilt on the market now.

    • Travis on April 25, 2020 at 9:39 am

      That sounds awesome. WM also got back to me and offered to change out the shell fabric as well, but unfortunately I didn’t send it in before they shut down for the virus. Good to know about the upgrades.

  22. John Vance on May 12, 2020 at 8:32 am

    I contacted Western Mountaineering to ask about modifying my quilt by opening up the back of the quilt further to aid in venting the lower leg and foot-box area. After a short discussion concerning this, they offered to make me a new quilt as well. I selected the navy blue 12d material that is used in the Megalite bag and also requested that the footbox be made shallower by 2.5 baffles. I now have 12 nights in the quilt with half of those in relatively high humidity conditions and the quilt has performed perfectly with no noticeable condensation build up.
    In addition, I too received the quilt with the new quilt to pad attachment system that is very similar to the system on other quilts, most notably those like EE quilts. I don’t attach my quilt to the pad but I really like Western Mountaineering’s addition of short pieces of strap with small flat buckles that are sew to the quilt that allow the quilt to be closed up with some width adjustment without using the strap that goes around the pad.
    I sent my quilt in the first of the year and the whole process was about 6 weeks as they had it ready in time for a planned trip in February in southern Utah. World class quilt from a world class company that understands what customer service really means!

    • John Vance on May 12, 2020 at 8:35 am

      I should note that my original regular length quilt came in at 16.5 oz without any straps and the new quilt came in at 17.3 oz with the sewn on short straps and clips.

  23. Eric Schwind on October 8, 2020 at 11:33 am

    Are there any 5’10” users out there? wondering if the 5’8″ version is too short, although the website says for people under 6 feet.

    • John Vance on April 2, 2021 at 9:40 am

      At 5″10 you are certainly on the edge of moving up to the longer bag. I am 5’9″ with size 12 feet and while on my back I feel like I am at my comfort limit for the regular sized quilt. I sleep on my side mostly so it isn’t an issue but if you are a back sleeper I would most likely pull the trigger on the larger quilt.

  24. Anika on June 4, 2022 at 3:29 pm

    Do you happen to have any opinions on how to consider this temperature rating in comparison to bags rated for women? I haven’t been able to find much information on this anywhere.

    For reference, I’m a relatively warm sleeper for a woman anyway, and was generally too warm (never used my hood or even zipped up the bag) in my Feathered Friends Egret 20 on the JMT in late June/early July last year. I am wondering if this could be a good option for me, but I’m concerned it might be too big a jump and I would be too cold on JMT/similar hikes in the Sierra. I’m happy to sleep in my down hoodie when needed & will bring the xtherm, but I don’t want to push it so far that I’m suffering!

    • Andrew Skurka on June 5, 2022 at 12:53 pm

      Western doesn’t subscribe to the EN testing system (and it couldn’t anyway for a quilt) but I’d trust their ratings as a good “comfort” level.

      If you tend to sleep warm, the ratings are probably accurate for you, maybe even conservative.

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