Camping in Winter: How to Stay Warm While Sleeping Outside
What do I Know about Sleeping in the Cold or Winter Camping?
I am an avid hiker, camper, and backpacker. As I write this article on sleeping warm and comfortably while camping, I have slept outside about 30 nights this year, primarily in the Sierra Nevada mountain range in California, at times in temperatures that dipped into the lower 20s. I backpacked about 170 miles of the John Muir Trail this year, where overnight temperatures dipped into freezing, and carried my sleep system on my back for my entire journey, forcing me to invest my time in research and make purposeful decisions about what to bring upfront. After some experiences shivering while camping over the years, I have dialed in my sleep system to be optimal for me and would like to share my experiences to help others avoid a night of discomfort from the cold.
Sometimes Camping can be Cold
But Braving the Cold can be Completely Worth it
Essential Elements of a Sleep System
- Insulated Sleeping Pad
- Sleeping Bag
- Appropriate Clothing and Additional Insulating Layer if Necessary
- Tricks to Getting Warm and Staying Warm
My Insulated Inflatable Sleeping Pad - Right Combination of Size, Weight, Warmth, and Comfort for me
Sleeping Pads: A Crucial Source of Insulation
A sleeping pad provides campers with comfort and necessary protection from the heat-robbing abilities of the ground. The ground pulls an incredible amount of heat away from a camper’s body, so insulation under a sleeping bag is necessary in the winter. Additionally, if a sleeping bag has down insulation, the down will compress under the user’s body, leaving the user’s back unprotected by insulation from the sleeping bag.
Closed cell foam – Closed cell foam pads are generally the cheapest and most durable type of sleeping pad available and are often made of metallically coated foam that can reflect body heat back to the sleeper. These are generally lightweight but bulky, but are a very cost effective way to boost warmth when sleeping.
Inflatable – These lightweight pads are much smaller than their foam cousins and are generally inflated by manually blowing into them or using a pump. If choosing an inflatable pad, be sure to verify that it is an insulated inflatable, as not all inflatable sleeping pads are designed to keep their users warm. Typical insulated inflatable pads will have heat-reflective Mylar (think space blanket) sandwiched between the outer layers.
Self-inflating – Self inflating pads are a compromise between foam and inflatable pads, combining attributes of each. These pads contain open cell foam that expands when the pads’ valves are opened and do not require manual inflation as the foam expands fully when exposed to air and not compressed. These tend to be more comfortable than the above alternatives, but are generally heavier.
For true winter camping, insulated pads can be used together to stack their insulating properties. I often use a closed cell foam pad beneath an insulated inflatable when I camp in freezing temperatures.
Insulation, in regards to sleeping pads, is measured using what is called an R value. This is the measure of the pad's resistance to heat transfer, so the higher the R value, the warmer a pad will keep its user. For further explanation of R Value and some of the science behind it, watch the following video.
Insulation and R Value Explained
Sleeping Bags: It's All About the Temperature Rating
There are many choices one can make when choosing a sleeping bag: temperature rating, down vs synthetic, mummy vs rectangular, etc. The most impactful of these choices is the temperature for which their bag is rated.
Sleeping bags often come with a numerical temperature rating. These temperature ratings should always be considered a lower limit of use rather than a temperature at which the user would be comfortable sleeping. Unless the bag has an “EN rating” the temperature rating is at the discretion of the manufacturer and is not scientifically tested.
Additionally, common advice dictates to not take a bag into weather lower than 10 degrees above its lower limit. For example, a 20 degree bag (the most common “3 season” temperature rated bag) can be used comfortably down to about 30 degrees if the user is wearing appropriate clothing and has an insulated sleeping pad.
Sleeping Bag Temperature Ratings Explained: European Norm (EN) Rating
Has the Cold Ever Deterred You From Camping?
Has the Cold Ever Deterred You From Camping?
Stay Warm in Your Sleeping Bag
Clothing – Wear a hat, warm socks such as wool hiking socks, and warm clothing. Hats are generally recommended to keep the wearer from losing heat through their head. This is absolutely critical if the sleeping bag being used does not have a hood. I generally wear a wool shirt and long underwear as my warm clothing if sleeping in the cold and wear a hat even under my hood if it is really cold.
Vests and Coats – If all else fails or temperatures have sunk lower than expected, a vest or coat can be worn during sleep to supplement the insulation of one’s sleeping bag. Many ultralight backpackers use their down vests and coats within their sleeping bag as part of their comprehensive sleeping system and as a way to carry a lighter sleeping bag rated for use in warmer temperatures. I almost always hike and camp with a lightweight down vest because I can wear it comfortably when awake or sleeping.
Use a Tent – A tent will help capture body heat and can much more comfortable from a temperature perspective than sleeping under the stars. A double wall tent is a tent that has two layers, usually a mesh or thin solid inner and waterproof outer fly, that will keep occupants warmer than the single wall counterparts. To decrease the chance of condensation forming and getting the occupants wet, make sure the tent has a vent and/or leave part of the outer rainfly out to ventilate the tent.
Hot Water Bottle – A camper can heat some water before bed, fill a water bottle such as a Nalgene with the hot water, wrap in a shirt or a sock, and stuff at the bottom of their sleeping bag. This will help heat up the sleeping bag quicker than with just one’s body heat and will additionally help keep the camper’s feet warm. Also, too much unused space in a sleeping bag means that there is extra room that needs to be heated, resulting in a longer time needed to warm up the sleeper. A hot water bottle, or even extra clothing can be utilized to effectively shrink the unused space in a sleeping bag
Eat Enough Calories – Our bodies require calories to burn for energy. If we do not eat enough calories, our bodies will lack the fuel needed to produce more heat. I have witnessed first-hand: after an aggressive all day hike/climb for which I did not consume adequate calories, I spent much of the night shivering in my sleeping bag that was rated for much colder than the temperature at the time. Make it a practice to eat something before bed - favorites are chocolate bars or hot chocolate for some fast sugar calories.
Go to the Bathroom Before Turning In for the Night – our bodies use heat to keep urine warm, so make sure to go to bed with an empty bladder to conserve heat.
Stay Warm Before Bed – If your core temperature is cooler before bed, it will take you even longer to warm up in your tent and sleeping bag. It is sound advice to not let oneself get cold before going to sleep. Many through hikers and backpackers will often go to sleep early in the evening before temperatures drop in order to avoid cooling down their core body temperature.