Gear Review: NEMO Equipment Sonic -20° Down Ultralight Mummy Sleeping Bag
The NEMO Sonic -20° Down Sleeping Bag is built for extreme cold, offering ultralight warmth, packability, and comfort. Perfect for winter backpacking and alpine expeditions, its innovative design keeps you cozy in the harshest conditions. Discover if it's the right fit for your adventures!
Winter camping is one of my favorite ways to experience nature and wild places. And of course, winter is unavoidable living in the San Juan Mountains of the Southwest! There is a lot that goes in to staying safe while camping in freezing cold temperatures, but a key to winter camping safety is an awesome down sleeping bag to keep you warm. This year I have been relying on NEMO Equipment's Sonic -20°f Down Ultralight Mummy Sleeping Bag.
Ultralight and winter camping are not usually two peas in a pod, so I was very curious to start using the Sonic -20°. It weighs in at a very scant 3 pounds, 14 ounces and compresses down to a very small size, easily fitting into a 60 liter backpack. After using it on a handful of frigid backcountry adventures, I've gotten a good feel for what this sleeping bag is capable of!
Quick Rundown of the NEMO Equipment Sonic -20° Down Ultralight Mummy Sleeping Bag
- Packed size: 14.5 x 10.5 in diameter
- Weight: 3 pounds, 14 ounces for the regular size
- 800 fill power down
- Fill weight: 2 pounds, 5 ounces
- Zipper located on left
- Waterproof yet breathable footbox uses a layer of synthetic insulation to protect the down fill
- Stretch construction at the knees makes for comfortable side sleeping
My Experience with the NEMO Equipment Sonic -20° Down Ultralight Mummy Sleeping Bag
This year I have used the Sonic -20° Down Ultralight Mummy Sleeping Bag on three winter camping trips, with one being a backpacking trip. I have used a few different extreme-rated sleeping bags in my pursuit of winter exploration and my initial thought with the Sonic -20° was that is compresses down extremely small. Which is exciting, as it frees up some valuable pack space!
The draft collar and draft tube on this sleeping bag are big and burly, and best of all they're incredibly effective in blocking out cold air. I am 5'6" and the regular size bag fit me well. It's snug and gives me enough space to move, but it's not spacious. This means that it is a good fit and insulates appropriately.
So let's get into my experience a bit. On all three winter trips I used this sleeping bag for, I was in the high desert and overnight lows ranged from -5° to 15°. For men, this may not be a range where you'd require a -20° sleeping bag. But for women, I find that this range is super tricky and if you sleep cold to begin with, erring on the side of a warmer sleeping bag is a must.
If it becomes too warm in the bag, there are two very effective vents over the chest that can be unzipped both on the inside and outside of the bag. They are NEMO's Multistage Thermo Gill Zippered Vents. I did not need to use them in this range, but if temperatures had gotten much warmer, I likely would have been unzipping them. I use them in my CODA sleeping bag often!
On two of the camping trips I used the Sonic -20° Ultralight on, condensation was an unavoidable issue, and tent sag was a bit of an overnight problem. These two things combined lead to a wet inside of the tent. Not great for well below freezing camping. Where this can create bigger problems is when your down sleeping bag gets soaked and freezes up. Thankfully the down in this bag is hydrophobic, but the real MVP in these scenarios was the waterproof foot box that also includes a bit of synthetic insulation to keep the down lofted.
My sleeping bag never got wet with condensation and moisture was never an issue. Whew. Ain't nobody got time for that!
NEMO Equipment claims that there is stretch in the knee area of this sleeping bag. It's not something you really notice, but it's obviously there based on the comfortable side sleeping with this bag. A lot of times super warm sleeping bags can feel restrictive when laying on your side. The Sonic -20° is far and away the most comfortable extreme sleeping bag I've used when it comes to that.
So what are the negatives of the Sonic -20°? At this point I'm not super sure. It seems like a perfectly crafted mix of extreme temperature coziness and effective ultralight design. Would I be comfortable sleeping in it down to -20°? Absolutely not, but that's pretty par for the course. Temperature rating and comfort rating are two very different beasts.
I have a whole lot more backpacking trips and frigid camps in store for this winter, so I will be sure to come back and update this as the outdoor sleeps stack up!
If you're looking for an ultralight down sleeping bag for ultra-freezing cold camping, the Sonic -20° Down Ultralight Mummy Sleeping Bag by NEMO Equipment is likely perfect for the adventures you'll get up to!
Sonic -20° Down Ultralight Mummy Sleeping Bag by NEMO Equipment: Pros and Cons
The Sonic -20° Down Ultralight Mummy Sleeping Bag by NEMO Equipment offers ultralight warmth and innovative features for cold-weather adventurers. Check out the pros and cons below:
| Pros | Cons |
|---|---|
| Extremely warm | The temperature rating is likely exaggerated and more like -8° |
| Exceptional venting | |
| Waterproof footbox | |
| Unbelievably ultralight and compressible |
Click here to learn more and purchase the Sonic -20° Down Ultralight Mummy Sleeping Bag by NEMO Equipment for your next expedition!
My review is independent of the supplier and reflects my own opinions. Some of the links on this page are affiliate links, which means I may receive a small commission if purchases are made through those links at no additional cost to you.
