When determining if a 20 degree sleeping bag will be warm enough, there are a few key factors to consider:
1. Your Personal Comfort Level
The first consideration is your own personal comfort level and sensitivity to cold temperatures. Some people tend to sleep hot, while others sleep cold. 20 degrees may be plenty warm for some sleepers, while others may require a warmer bag closer to 0 degrees for the same conditions.
Think about your past camping experiences and how you have felt in other sleeping bags at various temperatures. If you tend to sleep cold and want to ensure you stay warm throughout the night, a 20 degree bag may leave you feeling chilly.
2. Weather and Environmental Conditions
The forecasted overnight low temperature is important, but you also need to factor in humidity, precipitation, and wind chill. A 20 degree bag will feel much different in dry conditions versus damp, windy conditions. The same 20 degree bag can feel inadequate if there is high humidity in the air or you are sleeping on cold, damp ground.
You’ll want to check the weather report to see the predicted low temps, chance of rain or snow, and if high winds are expected. Plan for about 10-20 degrees colder conditions to account for wind chill and humid conditions.
3. Type of Camping Shelter
Your sleeping shelter makes a big difference in how warm your sleeping bag will need to be. A tent can retain some body heat and provide protection from wind and elements. A sleeping bag that may be warm enough for tent camping may not cut it for sleeping under the stars next to a campfire.
An insulated shelter like a small camper or RV can allow you to get away with a slightly lighter sleeping bag as well. The type of padding or sleeping pad you use also impacts warmth. Foam pads provide more insulation from the cold ground than thin inflatable pads.
4. Duration of Your Trip
How many nights you will be camping is important to factor when choosing a sleeping bag. You may be able to get by with a 20 degree bag for a single overnight trip in Fall conditions. However, that same bag will likely not be warm enough over several nights as your body becomes fatigued andyou lose body heat.
Plan for a warmer temperature rating if you will be camping for a week or longer, even in above freezing conditions. Your body temp can drop over several cold nights of sleep, so go warmer than the expected low temp for long trips.
5. Clothing and Layers
The clothing and layers you wear to sleep will impact how warm your sleeping bag needs to be. Wearing thermal base layers, wool socks, and a hat can allow you to sleep warmer in a 20 degree bag compared to just wearing PJ’s.
You lose a lot of body heat from your head and extremities. Proper layers hold in that valuable body heat. You can compensate for a slightly colder bag by wearing more insulating clothes and socks to bed.
6. Use a Sleeping Bag Liner
Adding a sleeping bag liner provides extra warmth and insulation for your current sleeping bag. Liners add around 10-15 degrees of warmth. So a 20 degree bag with a liner can get you down to cold temps close to freezing.
Silk and fleece liners work well. You can also purchase sleeping bag wraps that act as a liner and help trap heat. Using a liner allows you to stretch your current bag’s temperature rating at a lower cost than buying a completely new one.
7. Use a Hot Water Bottle
A simple hot water bottle filled with heated water and placed in your sleeping bag is an easy way to boost warmth, allowing a 20 degree bag to work for colder nights.
The hot water bottle simulates your own body heat and allows you to warm up the bag before getting in. The residual heat warms your extremities and keeps you cozy for hours. Just be careful not to overheat or accidentally tip the bottle once inside your bag.
8. Eat a High-Calorie Dinner
Eating a substantial dinner with plenty of carbs and some fats can also help boost your body temperature at night. Your body has to metabolize these heavier foods and burn calories to generate heat.
Choose foods like chili, oatmeal, pasta dishes, meaty stews, and nut butters. Avoid cold salads and foods that can drop your core temp. The extra calories from hot, hearty foods keep your internal furnace stoked through the night.
9. Bring Hand and Toe Warmers
For very cold nights around 20 degrees or below, pack some single use hand and toe warmer packs. These air activated pouches provide up to 10 hours of heat. Placing them in your sleeping bag helps stop toes and fingers from getting painfully cold.
You can also keep them in your pocket while outside the tent at night. Pair them with thick wool socks and insulated gloves to retain heat in those easily chilled extremities when sleeping in frigid temps.
10. Use a 0 Degree Sleeping Bag
One of the surest ways to stay warm on nights dipping into the 20’s is using a thicker, insulated 0 degree Fahrenheit sleeping bag. While bulkier and more expensive, a 0 degree bag essentially guarantees you’ll stay warm in freezing and sub-freezing overnight conditions.
For cold-sleepers and minimalists using lighter shelters like tarps, upgrading to a warmer 0 degree bag eliminates the need to pack extra blankets, jackets, and layers to sleep. A winter-rated bag gives you that built-in warmth for cold weather trips.
The Best Temperature Rating for a 3 Season Bag
For most campers who only occasionally venture out into cooler Fall and Spring conditions, a sleeping bag rated between 15-25 degrees Fahrenheit is ideal for a “3 season” bag.
Bags rated to 20 degrees provide versatility to handle nights down into the 30’s while still being lightweight enough for Spring and Summer camping. Aim for at least 15-20 degrees for your primary 3 season sleeping bag.
Key Factors When Choosing a Cold Weather Sleeping Bag
When shopping specifically for a sleeping bag to handle colder temperatures, keep these factors in mind:
- Choose a mummy-style bag shape to retain heat versus rectangular bags
- Look for a higher fill-power goose down or synthetic insulation
- Make sure the draft tube and collar are well-insulated
- Get a bag with an EN rating for the lowest possible temp range
- Look for draft-blocking features like an insulated hood, draw-cord, and full length zipper baffle
- Consider water-resistance features if camping in snow or damp conditions
Paying attention to these cold weather specific features ensures your bag is equipped for the coldest environments and conditions.
Use Multiple Sleeping Bags
An option some campers use in very cold weather is layering two sleeping bags for extra insulation. This lets you get incremental warmth by combining the temperature ratings of each bag.
For example, layering two 20 degree F bags essentially creates one very warm -20 degree bag. The only drawback is bulk and weight, but for car camping in freezing weather, two bags work well.
You can also put a light or summer weight bag inside a heavier winter bag. The inner bag helps keep the insulation lofted. Just make sure the bags are wide enough to comfortably layer them.
Survival Tactics for Insufficient Sleeping Bags
If you ever end up camping in colder weather than your current sleeping bag is rated for, there are some emergency tactics to stay warmer at night:
- Wear all your dry clothing to bed, including hats, gloves, socks
- Use a vapor barrier or trash bag over your legs and torso inside the bag
- Fill a nalgene water bottle with hot water and keep it in your bag as a heater
- Use mylar space blankets under and over your sleeping bag
- Sleep closer to campfires or stoves to absorb radiant heat
- Get in your vehicle or sleep inside to escape wind chill if needed
While not ideal, these methods can get you through a night without freezing when your sleeping bag is not designed for extreme cold.
Sleeping Bag Temperature Rating | Recommended Use |
---|---|
50-40°F | Summer camping |
30-20°F | 3 season camping |
15-0°F | Cold weather camping |
-10°F and below | Extreme cold and mountaineering |
This table displays general guidelines for choosing a sleeping bag based on the typical temperature range you plan to camp in.
Conclusion
On its own, a 20 degree sleeping bag can be a bit marginal for camping into freezing and below freezing temperatures. With some cold weather sleeping aids like liners and warm layers, a 20 degree bag can work for Fall and Spring trips where lows hover in the 30’s.
However, for optimal comfort on colder camping trips, choose a sleeping bag rated closer to 0 degrees Fahrenheit. This will ensure you stay warm all night. As always, your individual comfort level, trip conditions, and other gear factor into whether a 20 degree bag provides enough warmth.