By Michael Lanza

Head into the mountains in summer, or almost anywhere in fall or spring, and you can encounter nighttime and morning temperatures anywhere from the 40s Fahrenheit to well below freezing. That’s more than cold enough to pose a real risk of hypothermia or, at the least, result in a miserable night for you or a partner or child you’ve taken backpacking or camping—and would like to take more. Here’s the good news: The very simple techniques outlined in this article can turn a potentially unpleasant night into a comfortable one.

Countless frosty nights sleeping outside over the past three-plus decade—including many years as a past field editor for Backpacker magazine and running this blog—have taught me a few things about how to stay warm. (My coldest night was -30° F, in winter in New Hampshire’s White Mountains. I don’t recommend it.)

No matter how easily you get cold when sleeping outside, or whether you’re camping in the backcountry or at a campground, these 10 tips will keep you warmer on cool and chilly nights in your sleeping bag.

Tell me what you think of my tips, ask any questions, or share your own tips in the comments section at the bottom of this story. I try to respond to all comments.


Hi, I’m Michael Lanza, creator of The Big Outside, which has made several top outdoors blog lists. Click here to sign up for my FREE email newsletter. Join The Big Outside to get full access to all of my blog’s stories. Click here to learn how I can help you plan your next trip. Please follow my adventures on Facebook, Twitter, Instagram, and Youtube.


 

#1 Clean Up

At the end of each hiking day, wash the dirt and dried sweat from your body; the latter can act like a heat conductor, chilling you, and getting a bit cleaner will just make you feel better. Swim in a lake, wade into creek and splash water all over yourself, or at least wet a bandanna or other cloth (or use wet wipes or other such products) and wipe yourself off.

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The Nemo Kyan 20 synthetic sleeping bag.
The Nemo Kyan 20 synthetic sleeping bag. Click photo to read my review.

#2 Change Into Dry Clothes

Damp clothes promote conductive heat loss from the body. Change into dry clothing to sleep, as opposed to the clothes you sweated in while hiking.

#3 Dress Smartly

Inside your bag, wear a hat, socks, and extra layers on your body, but avoid putting on so many layers that you isolate your core, which is your body’s furnace, from your extremities, which get cold more easily. It’s often more effective to wear just one or two light to midweight layers (think: one or two base layers, or a base layer and a light insulation piece) on your body and line your bag with other extra clothing, which provides added insulation for your entire body.

Feathered Friends Hummingbird UL 30.
The ultralight but very warm Feathered Friends Hummingbird UL 30. Click on the photo to read my review.

#4 Use a Hot-Water Bottle

Stick a water bottle (like a plastic Nalgene bottle, not an insulated or vacuum bottle, which would not release any heat) filled with hot water in the foot of your bag. If that’s not enough, put a second bottle filled with hot water in the middle of your bag. (Make sure they’re sealed tightly.)

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#5 Sleep on Insulation

Use an insulated pad or air mattress rated for the lowest temperatures you expect to encounter. Mats and pads with an R-value of between 3 and 4 are intended for three-season temperatures—generally, above freezing—while those with an R-value of over 5 are intended for use on frozen ground in below-freezing temperatures. If needed, add a second foam pad under your primary air mat if you’re sleeping atop frozen ground or snow.

Therm-a-Rest Hyperion 32F/0C sleeping bag.
The one-pound Therm-a-Rest Hyperion 32F/0C sleeping bag. Click on photo to read my review.

#6 Augment Your Sleeping Pad

If you’re using a short air mattress or foam pad (to save weight in milder temperatures), lay your empty pack beneath your feet to insulate them from the ground, which can drain heat from your body even in summer. Or bring a short foam pad to provide more padding and insulation under a full-length air mat.

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A backpacker at a campsite on the Teton Crest Trail in Grand Teton National Park.
Todd Arndt at a campsite on the Teton Crest Trail in Grand Teton National Park. Click on the photo to see more images from that classic trip.

#7 Pile Extra Clothing Underfoot

Your feet get cold more easily than other body parts because they lie the farthest from your heart and, inside a sleeping bag, are not close to your furnace: your body’s core. They can also get cold because the ground under your sleeping pad is cold. Pile extra clothing under the foot end of your bag to give your feet more insulation against the cold ground.

#8 Use a Bag Liner

Use a sleeping bag liner, which can add the equivalent of several degrees of warmth rating to a bag.

Never get cold again (well, almost never). See my “5 Tips For Staying Warm and Dry While Hiking.”

 
The Sierra Designs Nitro 800 20-Degree sleeping bag.
Testing the Sierra Designs Nitro 800 20-Degree in the Wind River Range. Click on photo to read my review.

#9 Eat Some Fat and Sugar (The Fun Tip)

Eat a snack high in fat right before bed, like a candy bar, and have a hot drink with sugar in it, like hot cocoa. Both will fuel your body’s furnace through the night.

#10 Use Your Partner

If you’re sharing a tent with a partner who doesn’t get cold as easily as you, ask that person to sleep on the tent’s windward side. If you have two warm-sleeping partners, sleep between them, or at least position your bags and pads close together to benefit from one another’s body heat.

Tell me what you think.

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See my “Pro Tips For Buying Sleeping Bags” and all of my reviews of sleeping bags, air mats, and backpacking gear that I like.

Whether you’re a beginner or seasoned backpacker, you’ll learn new tricks for making all of your trips go better in my “12 Expert Tips for Planning a Wilderness Backpacking Trip” and “A Practical Guide to Lightweight and Ultralight Backpacking.” If you don’t have a paid subscription to The Big Outside, you can read part of both stories for free, or download the e-guide versions of “12 Expert Tips for Planning a Wilderness Backpacking Trip” and the lightweight backpacking guide without having a paid membership.

 

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