The Best Winter Sleeping Bags of 2024
This article originally appeared on Outside
If you've never tried it, we're here to tell you that sleeping outside in the winter is way more fun than it sounds. Today's winter bags are constructed like mobile sleep spas: Our three favorites for 2024 are so technical and luxurious that they outpuff the comforters at most five-star hotels. With water-repellant outer fabrics and silky, breathable interior liners that keep damp--and stink--at bay, cozy hoods that cradle your noggin on a billowy pile of down, and roomy-yet-swaddling mummy shapes, these three bags put our testers into deep hibernation, even when temps dropped below zero. The challenge was waking up the next morning to face the cold.
The Winners at a Glance
Most Versatile: NEMO Sonic Down Mummy
Most Comfortable: Feathered Friends Widgeon ES -10 (men's), Arctic Finch -10 (women's)
Best Expedition Bag: Therm-a-Rest Polar Ranger -20
The Reviews: The Best Winter Sleeping Bags of 2024
Most Versatile: NEMO Sonic Down Mummy ($600)
Weight: 3 lb, 4 oz (Regular)
Size: Short, Regular, Long
Pros:
Great temperature regulation
Cons:
Small top vent zipper pulls
Tiny exterior pocket
The Sonic mountaineering mummy was already Minnesota-based tester Patrick Greehan's go-to bag for winter camping. And that was before NEMO gave it a significant upgrade last year, improving its ability to adjust to varying temperatures, giving it greater warmth retention, and making it more sustainable. We're happy to report that over three campouts, nestled in a bivvy sack atop multiple feet of packed snow in northern Minnesota, with temperatures that ranged from three to 20 degrees Fahrenheit, Greehan slept better than ever before.
The most notable upgrade for Greehan was the bag's redesigned "Thermo Gills," the two vents on top of the bag that can be opened or closed to regulate body temperature. The improved gills, which run vertically down the top half of the bag, now have internal and external zippers that work independently of each other to more finely tune ventilation and comfort. On the 20-degree nights when he fully unzipped, he was able to prevent himself from overheating. On the three-degree nights, he remained in that same comfort zone by zipping them back up.
To improve warmth retention, NEMO redesigned the draft tube along the side zipper and added a velcro tab to the draft collar to keep cold air from sneaking in. New chevron-shaped baffles hold the 800-fill power hydrophobic down in place and provide more uniform lofting. As a back and side sleeper, Greehan was able to snooze in both positions with no cold spots. A layer of synthetic insulation in the toebox protected the down from wetting out, a common occurrence at the bottom of a bag.
To complete the overhaul, NEMO updated the shell and liner fabrics, using plush, 100-percent recycled, bluesign-approved nylon for the shell and a silky, 100-percent recycled polyester for the liner.
Other exceptional features? The roominess of the hood, which Greeham could cinch tightly if needed, the bag's excellent packability--it scrunches down to an XXL roll of paper towels despite an only average weight--and a robust zipper that never got caught up on the lining.
Bottom Line: With its versatile temperature range, solid construction, and impressive packability, the NEMO Sonic Down Mummy is the only winter bag most of us will ever need.
Most Comfortable: Feathered Friends Widgeon ES -10 ($889)
Weight: 3 lb, 2 oz (Regular)
Size: Regular, Long
Pros:
Extremely warm and comfortable
Cons:
Narrow footbox
The Widgeon cocooned our testers in so much warmth and silky comfort that they could have happily hibernated all day. Already a frigid-weather favorite, the handmade-in-Seattle bag--originally designed for a K2 expedition back in the '80s--received a major facelift this year. Feathered Friends added three additional ounces of responsibly-sourced 900-fill power goose-down. That down is sandwiched between a gossamer 10-denier nylon Pertex taffeta lining made from PFC-free recycled yarns and a water-resistant, breathable Pertex nylon shell with a DWR coating. The collar and hood keep your face snug, warm, and protected (but not claustrophobic) thanks to a gradually contoured cut. It can be cinched nearly all the way closed using a nylon cord that runs around the perimeter of the top of the bag.
With all that plush comfort, one might think the bag would sleep too hot. But even when camping in late March, Duluth-based tester Brian Hayden and category manager Stephanie Pearson never overheated while cowboy camping in temps that ranged from 15 to 28 degrees--balmy compared to its negative ten degree rating. The reason? An additional Pertex nylon panel over the top of the bag vastly improves its breathability and venting. That Pertex layer blocks moisture, too: Despite waking up to a thick layer of hoar frost, they stayed dry in their bags, even as the morning sun warmed their tent.
Additional small-but-mighty upgrades include a second sidewall to ensure even insulation all around the circumference of the bag; more streamlined internal construction that cuts weight despite the extra down, and a generous draft tube to stop cold air from seeping through the zipper. That might sound like splitting hairs, but every warmth-preserving measure matters when you're winter camping--especially on the flanks of K2. And, for a bag so lofty, it packs down impressively to the size of a 64-ounce beer growler.
Bottom Line: The Widgeon's warmth-to-comfort-to-weight ratio is exceptional for nights in the zero-degree range.
Best Expedition Bag: Therm-a-Rest Polar Ranger -20 ($790)
Weight: 3 lb, 4 oz. (Regular)
Size: Regular, Long
Pros:
Side zips for venting and hand-use
Cons:
Three-quarter zipper is hard to get in and out of for taller sleepers
The Polar Ranger was one of the best expedition bags on the market when it came out in 2018 thanks to polar explorer Eric Larson, who helped design the mummy for its natural environment. The result was a pioneering three-quarter length zipper straight up the middle to cut weight and increase warmth. Zippered side vents made it possible not only to dump heat, but also sit up, shoot your arms out, and do anything from write in a journal to fiddle with a sat phone. "In an expedition situation, every ounce of energy saved is key," Larson explained over email. "After spending years of my life in a sleeping bag, I found full length zippers unnecessary in most situations."
But the Polar Ranger wasn't without its imperfections. The newest iteration comes with a slew of upgrades that make the bag even more livable. A fresh, 100-percent recycled DWR-coated nylon ripstop shell and a buttery-smooth 100-percent recycled nylon liner are silky to the touch. The newer version is also slightly larger in both length and girth after feedback from the field that the bag was too tight with heavy winter layers on. A redesigned snorkel hood is stiffer and shorter, too, which means improved breathing and ventilation, with a magnetic closure that makes it easy to break free in case of a claustrophobia emergency. Small but critical details? An added internal drawcord in the draft collar for cinching the bag around the neck and shoulders, and an internal pocket for keeping small electronics warm.
Our testers found the 800-fill hydrophobic down bag up to the task of keeping them warm on a -10 degree overnights with lots of wind in Minnesota's Boundary Waters Canoe Area Wilderness. "I used the arm holes way more than I thought I would," reported Minnesota-based tester Hansi Johnson who, as a side sleeper, was also impressed with the roominess of the bag and how it maintained its loft on all sides as well as on the back. The snorkel hood, on the other hand, took a little getting used to. "It felt claustrophobic at first, but it kept moisture off my face. I was so warm I tossed my Buff."
Bottom Line: If you have an Arctic expedition or winter mountaineering project in your future, this is the bag to take along.
How to Buy
As a general rule, men tend to run hotter and women tend to run colder--although, as with anything, there is a spectrum. Throw in varying sleeping positions, body shapes, and sizes, and it's quickly evident that while some bags offer superior materials and design, there's not one magic winter bag that works for all. To find the one that will work best for you, here are four things to consider that keep you from investing a significant chunk of change in the wrong bag.
Intended Use
Are you purpose-buying the bag for a specific mission like Eric Larson's 14-day Svalbard Expedition or to climb Denali? If so, you'll need one with an excellent warmth-to-weight ratio that will be relatively easy to haul, yet keep you warm enough in potentially life-threatening situations. Or do you intend to use it on shorter missions like weekend ice-fishing jaunts into Minnesota's Boundary Waters Canoe Area Wilderness? In that case, you'll likely be hauling a sled and will have fewer size and weight restraints. Or maybe you need an ultralight bag for a winter bikepacking trip that you can strap to your handlebars and only use in case of an emergency. Whatever the reason for buying the bag, think through the logistics of the journey and how that will affect the size, weight, and warmth of the bag you want to buy.
Insulation
Down bags are generally warmer for their weight and more compressible than bags with synthetic insulation. But if down bags get wet, they lose insulating capacity and take longer to dry out than synthetic bags. Many manufacturers use down processed with a hydrophobic chemical that prevents it from absorbing as much water. Others keep the insulation dry with a water-repellant finish or fabric. Pay attention to fill power. That number measures the volume taken up by the amount of down in your sleeping bag; the more loft your sleeping bag has, the more efficiently it will trap warm air. It will also weigh less and pack down smaller than bags with a lower fill power rated to the same temperature. Synthetic bags are more affordable, and therefore an excellent choice for new campers who are unsure how often they want to sleep outside, or backpackers who are headed to wet environments.
Shape
Most winter bags are mummy bags or modified mummy bags. Traditional mummies have a hood that gently tapers into the bag, is wide at the shoulders and narrows all the way to the footbox. Mummies are great for winter because they minimize dead space inside the bag and help keep you warmer by giving air less space to circulate. Some people find them cozy and cocoon-like, others find them claustrophobic.
For claustrophobes, a modified mummy comes in handy. While it's generally tapered like a mummy, it's cut more loosely in certain areas. Some offer slightly flared footboxes to give your toes more room, while others are wider in the body to accommodate side sleeping. Some have hoods that gently taper into the bag, others have removal hoods.
Temperature Rating
All bags on the market have EN (European Norm) or ISO (International Standards Organization) ratings, which is a standardized, independent test across manufacturers. The most commonly used since 2017 is the ISO rating. Note: ISO stops rating at -20C/-4 F, which means your -20 degree bag may require a test run before you head into truly frigid conditions.
With these standards, most sleeping bag manufacturers use a sliding range of temperatures for which a bag can be used. The "Comfort Range" is roughly the temperature range at which the average female will remain warm. The "Lower Limit" is the temperature range at which the average male can remain comfortable. This Lower Limit number is the temperature rating of the bag. That being said, your temperature tolerance will depend on much more than your gender, so it's always best to err on the conservative side. Some bags offer a "Risk" range, which indicates the lowest temperature in which the bag should be used. At this temperature, the bag might not prevent hypothermia, but it may prevent death. It's always best to buy a bag rated ten degrees colder than the average temperatures you intend to use it in. For example, if you plan to camp in conditions no colder than 10 degrees, you'll want a 0-degree bag.
How We Test
Given the increasingly wild weather swings we've experienced from climate change in the last few years, we gave our testers--who were spread out between northern Arizona, Minnesota, and Norway--as much true winter time as possible. We started testing in mid-January and wrapped up the process in mid-April. During that 90-day window, temperatures swung from -20 to a freak 70-degree thaw. Northern Minnesota and northern Arizona had record snow years, which meant wintery wind gusts and white on the ground long after the calendar told us it was officially spring.
Each bag was sent to category manager Stephanie Pearson for testing before heading off to secondary testers around the globe. One tester took his kid ice fishing in Minnesota's Boundary Waters Canoe Area Wilderness in January. Another went to Lillehammer, Norway for a late winter camping trip. Others spread their testing out over the course of the three months, bikepacking and sleeping out in their backyards to catch frequent aurora borealis sightings.
After the season was up, Pearson gathered the data, compared notes, and picked the winners.
Number of Testers: 6
Number of Nights Slept Outside: 20
Coldest Night: -20
Warmest Night: 50
Highest Latitude Tested: 61deg6'54.5''N (Lillehammer, Norway)
Meet Our Lead Testers
Stephanie Pearson has winter camped at Mount Everest Base Camp, in the Swedish Arctic, and in northern Minnesota. A fitful sleeper, she often gets better rest outside in a bag than in her own bed.
Hansi Johnson is a lifelong backcountry camper. His go-to winter spot is the Boundary Waters Canoe Area Wilderness to camp, ski, and fish. Johnson works for the Minnesota Land Trust advocating for Minnesota's Natural spaces. He lives in Thomson, Minnesota with his wife Margaret and his son Tae.
Ian Derauf spent a year studying at a Norwegian Folk School based in Tromso, where he learned the art of survival in the Arctic. He recently graduated from St. Olaf College and is headed to Sitka, Alaska, where his warm winter bag will come in handy.
Chloe Leege, a recent graduate of Duluth East High School, competed on the Duluth Devo Mountain Bike team for six years and is an aspiring bikepacker. She will attend Northland College, an environmentally focused liberal arts school in Ashland, Wisconsin, in the fall.
Patrick Greehan is an assistant coach for the Duluth Devo Mountain Bike Program. He currently races gravel, mountain, and fat bikes with a focus on long distance and ultra events. He is an avid bikepacker who pedals year-round in Northern Minnesota.
Brian Hayden is the founder of the Duluth Devo Mountain Bike Program who has logged a few months in Antarctica in a former life. He's a reluctant winter camper, but can sleep through just about anything.
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