The Sierra Designs Cloud 35 is a zipperless, mummy sleeping bag with a sleeping pad sleeve and foot vent that lets you stick your feet out if you’re too warm at night. Weighing 23 ounces, it’s insulated with 800 fill power water-resistant DriDown with an adjustable hood and loose-fitting inner coverlet that drapes across your torso.
Specs at a Glance
- Weight: 23 ounces (Size Regular, actual tested)
- Insulation: 800 fill power DriDown
- Shell and Liner: 15d nylon ripstop
- Style: Mummy
- Lengths: Regular (6′ 0″), Long (6′ 6″)
- EN Rating: EN Limit Temp Rating: 26F / -3C, EN Comfort Temp Rating: 36F / 2C
- Shoulder/Hip/Foot Box
- Regular: 60″/58″/40″
- Long: 62″/60″/42″
- Sleeping Pad Width
- Regular: 20″
- Long: 25″
The idea behind the Cloud 35 is to give people the combine the best features of an ultralight quilt, namely low weight and ease of venting, with the best features of a mummy-style sleeping bag, namely a hood and draft-free sides. Therm-a-Rest had a similar mummy bag called the Haven Quilt (click for review) a few years ago when backpacking quilts were still a novelty, but it never caught on.
The Cloud 35 doesn’t have a side zipper to save weight, so you need to slide in and out of it through the main opening. It has a sleeping pad sleeve on the back, that helps give the bag structure while using the insulation provided by your pad.
The hood is fairly “flat” and doesn’t wrap around your face like many cold-weather bags that force you to sleep on your back. The hood has a drawstring to reduce its volume and constrict the opening. In warmer weather, the hood is convenient to hold a pillow when you don’t need the hood or can wear a hat to sleep.
The footbox has a horizontal vent in it, allowing you to stick your feet out if you want to cool off at night. Overlapping fabric in the vent prevents drafts when your legs lie on top of the vent inside the bag. People’s core temperature has a tendency to cool off at night after a few hours of sleep and a vent like this provides a good way to vent warmth when you’re too hot, but snuggle up inside when your body temperature drops later at night.
The front of the Cloud 35 has a crescent-shaped front opening above the chest down to the waist. It’s filled with a down coverlet that’s sewn to the right side of the Cloud, but not the left (so you can slide in), with a yoke shape along the top that drapes around the top of your shoulders much like a draft collar on a cold-weather sleeping bag. If you’re a back sleeper, the coverlet will stay on top of you all night, even though the left side is loose and not connected to the body of the Cloud 35 in any way. But if you’re a side sleeper or thrasher, there’s a very good chance that it will be inadvertently pulled aside and let cold air into the bag.
I know because I am a side sleeper (facing right) and used the Cloud 35 for a half dozen nights over late summer and into the autumn months. I woke up cold over 80% of the time because the Cloud 35 coverlet got pulled out of position at night, exposing my back and the left side of my body to the cold night air. It happened consistently.
I can’t understand why Sierra Designs didn’t insert a velcro patch or hook and loop closure system to keep the Cloud 35 coverlet attached to the left side, if only for side sleepers.
This must have also been a complaint with the Backcountry Bed, which has a similar coverlet design. It’s worth noting that Sierra Designs added two hook and loop attachment points to the new Backcountry Bed 700 (now available), to keep the unattached right and left sides of its coverlet from moving out of position at night and letting cold air into the torso area. They should have done the same thing with the Cloud 35. It wouldn’t have affected the weight or ‘conceptual-integrity’ of the sleeping bag at all.
What is good about the Sierra Designs Cloud 35? It’s lightweight, easy to vent in warmer weather, prevents side drafts, has a hood, and attaches to your sleeping pad so you stay on it all night. Unless you’re a side sleeper or a thrasher, it’s a perfectly viable option for a warm-weather sleeping bag.
But there’s no reason you can’t enjoy all of those other advantages using a slightly different gear selection like an ultralight quilt with a sleeping pad sleeve or attachment system, a sleeping pad, and hooded down jacket. While it’s nice to have a single item like the Cloud 35 sleeping bag that can fill all of your needs, there are alternative ways to achieve the same result that can provide better, even lighter weight results. Quilts are not nearly as cold or drafty as some people who have you believe, especially for warmer temperatures above 35 degrees. They can also be used as top insulation in a tent or hammock, something that a mummy bag is very awkward for, zipper or not. For example, I’m a big fan of the Sierra Designs Backcountry Quilt and would encourage you to compare it to the Cloud 35.
Disclosure: The author received a sample sleeping bag from Sierra Designs for this review.