Review: Sierra Designs Cloud 35 & 20 || Premium mummy/quilt hybrid

A cowboy camp with the Sierra Designs Cloud 35 in upper Cascade Creek on the Pfiffner Traverse.

For eight consecutive nights in July, I slept in the Sierra Designs Cloud 35, which is new for spring 2018 and which may establish a new sleeping bag category. SD describes it as a “zipperless mummy,” but it takes just as many design cues from top bags and quilts.

Review: Sierra Designs Cloud Sleeping Bag

I can think of at least three audiences for the Cloud:

1. An existing mummy bag sleeper who finds it overly restrictive, who rolls off their pad at night, and/or who are annoyed by snagging zippers.

When closed up, the performance of the Cloud is on par with a conventional mummy.

2. A new backpacker who want a lightweight sleeping bag with premium materials that is priced lower than comparable models from the likes of Marmot, Mountain Hardware, and Sea to Summit. And,

3. An existing quilt user who wants a less drafty bag for colder temperatures, but who fears being confined in a mummy after enjoying the freedom of a quilt. Personally, I’m in this camp.

But its versatility and variable girth are more quilt-like.

The Cloud features 800-fill power water-resistant DriDown and 15d shell fabrics. It is most suitable for backpacking, when warmth-per-weight is a paramount concern. For camping, comfort and cost can be prioritized ahead of weight. It will be available in two versions:

  • 35-degree (1 lb 7 oz, $270, blue)
  • 20-degree (1 lb 13 oz, $300, red)

Each version is available in two lengths: regular (up to 6-foot) and long (up to 6’6″; +$20).

The 20-degree will also be available as a women’s bag (1 lb 12 oz, $300), fitting up to 5’8″. It includes the same fill weight as the unisex 20-degree regular (14.8 oz), but since it’s proportionally smaller it should be a few degrees warmer; extra down was allocated to the footbox and top core. An EN test was not done for this version, as an expensive-saving measure.


The Cloud originated with SD’s admission that it’s innovative Backcountry Bed can not compete with traditional mummies or quilts on a warmth-per-weight basis, all things being equal (like fill power, shell fabrics, and sizing). It simply requires too much build, like overlapping panels, extra seams, and a pad sleeve.

The Cloud, however, can and does. The 35- and 20-degree versions are each just 1 oz heavier than the new Nitro bags, which are pure vanilla mummies that feature the same materials and sizing.

Zipperless mummy

The Cloud differs from a conventional mummy (e.g. the Nitro) in two respects. First, it has no zipper. Instead, the top of the Cloud from the waist to the shoulders is more like a comforter or quilt, detached from the bag’s side on sleeper’s left. Despite this zipperless opening, drafts should be minimal or non-existent: the comforter hooks around the shoulder, and it overlaps with the side insulation when the sleeper is laying down.

The top comforter tucks into the side of the bag and has a shoulder “hook” to eliminate drafts even without a zipper.

Second, the Cloud is technically a top bag: it features a sleeve on its backside, into which a sleeping pad should be inserted. From the waist to the shoulders, the Cloud has no insulation on its underside, instead relying on the insulating value of the sleeping pad.

The weight consequences of these design differences are mostly a wash. By eliminating the zipper and underside insulation and baffling, the Cloud drops weight. But the overlapping materials and pad sleeve add it right back.

Gram weenies may wonder if the pad sleeve is critical. It’s not, but I’d leave it alone — I think it’s advantages are worth an extra ounce. The pad sleeve prevents the user from rolling off the pad, and allows the user to rotate within the bag. And in the particular case of the Cloud, the sleeve keeps tension on the bag’s top side, helping keep open the hole.

The pad sleeve adds about an ounce of weight, but improves the tension on the comforter and prevents the user from rolling off the pad.

Variable girth and sizing

Versus a traditional mummy, the Cloud is less restrictive and it lacks a snag-prone zipper. It has one more advantage, too: variable girth, due to the overlap between its comforter and sides.

This feature is most meaningful to backpackers who supplement the warmth of their sleeping bag by wearing their hiking clothes at night. For example, the Cloud fit me perfectly on warm nights, when I slept in just my hiking shirt and underwear. But it remained a perfect fit on cooler nights, when I also wore my insulated jacket (and later removed it because I was too warm).

I’m 6-feet tall, weigh in the upper 150’s, and have a 40-inch chest. The regular-sized Cloud offered sufficient height and more than enough width.

Temperature rating

The 35- and 20-degree versions have both been EN-tested. Your nighttime comfort may not coincide perfectly with the EN test (thankfully, mine does), but at least it gives you apples-to-apples comparison data between sleeping bags.

During my July trip — on which I used a drafty open-sided tarp — nighttime temperatures were typically in the 40’s. I found the 35-degree bag amply warm. If I had sealed it up while wearing my hiking shirt, shorts, pants, lightweight fleece, and puffy jacket, I’m certain that I could have been comfortable with temperatures in the 20’s.

Room for improvement

My single criticism of the Cloud is the side-sleeping experience. In this position, my face was directed at the side of the bag, whereas a traditional mummy bag would have rolled with me. This problem is inherent with top bags, and was remedied easily enough — I tucked the side or top of the Cloud under my face.

Thankfully, I’m generally a back sleeper, so the Cloud worked for me. And it’s not as if mummies aren’t also flawed — active sleepers can roll completely off their pads or become utterly twisted inside of the bag.

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