There are a lot of different opinions on whether or not bivvy bags are effective at keeping hikers and backpackers warm. Some people swear by them, while others say that they don’t provide enough warmth to be worth carrying.
So which is it? Do bivvy bags keep you warm? In this blog post, we’ll take a look at the pros and cons of using a bivvy bag.
We’ll start by making sure we understand what a bivvy bag is and how it works. A bivvy bag (short for “bivouac”) is basically a waterproof covering that you put over your sleeping bag to protect it from moisture, such as dew or condensation, and to keep your sleeping bag clean.
They are light, portable, and cheap – the perfect combination for a piece of equipment that you put over your sleeping bag! However, even though they are great in some ways, bivvy bags have several drawbacks when compared to the traditional tent.
One disadvantage of bivvy bags is that while they do keep you warm, they don’t protect you from the wind. The protection they offer is mainly against moisture – not wind, sun, rain, or insects.
Although bivvy bags are cheap and lightweight, most tents aren’t nearly as expensive or bulky. The weight you save with a bivvy bag is negligible compared to the peace of mind you gain from having your own rain shelter.
There are plenty of other reasons why a bivvy bag can benefit you more than using a tent. Some of the benefits to using a bivvy bag include –
- Bivvy bags are cheap.
- They require less setup time than a tent.
- They’re smaller, lighter, and more compact than most tents – making them easier to carry while hiking.
But even with all these benefits – do bivvy bags keep you warm? The answer is… it depends. Bivvy bags are great because they protect your sleeping bag from moisture. But if it’s windy, they won’t keep you as warm because they don’t protect against wind.
Some of the benefits that using a tent can have over using a bivvy bag include:
- Tents offer more protection than bivvy bags. You can store your boots in them, change into dry clothes, and get away from the elements whenever you want to. I once used my bivvy bag when it was raining heavily and got soaked by coming into contact with the side of the bivvy bag, which was completely soaked by rain.
- Once you’re inside a tent, you have a place to cook your food and boil water. You can also use the ground around your tent as a secondary latrine area in case it’s more convenient than going into the woods.
- Tents are better for multiple people sleeping close together. It’s much easier to fit two people into a tent than it is to make room for two in a bivvy bag.
- Tents are much more comfortable, and can hold back heavy winds better than bivvy bags.
Can you sleep in just a bivvy bag?
You’ve probably seen ultralight hikers and backpackers sporting nothing more than a bivvy bag to keep them warm at night. But can you really sleep in just a bivvy bag?
The short answer is an emphatic yes.
I’ve spent many nights in a bivvy bag, on every continent but Antarctica, and have never felt too cold or miserable while doing so. That said, there are some things to watch out for when using nothing but a bivvy bag.
10 tips for sleeping in a bivvy bag
Wear appropriate thermal layers: Although some hikers swear by naked sleep, if you’re going to be spending the night outside in a bivvy bag, it’s best to wear clothes. Lots of clothes. If you run cold, this means having on enough warm layers so that you aren’t shivering all night. And if you run hot, this means having on more than just underwear and a bandana.
Consider using a sleeping bag liner: This is an invaluable piece of gear if you’re going to be spending the night outside in a bivvy bag. Even the lightest and thinnest sleeping bag liner will make your sleep exponentially warmer. They also make it easier to wash your sleeping bag in the morning, and add another layer of protection.
Pack a vapor barrier liner: Most bivvy bags are not completely waterproof (mine has an annoying sewn-in hole near my face), so having a way to keep out any moisture is pretty much mandatory if you’re going to be outside in one. There’s no better way than using a vapor barrier liner like VBLOC or OVFLOC . You can use these with a tent or a bivvy bag.
Choose the right spot: The best place to sleep for warmth is on top of cold ground, commonly known as ‘earth insulation’. Some people think that the colder the ground, the better the insulation. But this is actually wrong. If the ground freezes, below zero degrees Celsius, it becomes a bad conductor of heat and you can lose body heat much faster than usual.
Consider using a therma-rest mattress pad: As someone who’s used this for five years on every continent (except Antarctica), you can consider me an expert on these things. Therma-rest pads are some of the best gear I own, and if you’re going to be sleeping in a bivvy bag – one of them should certainly be packed if you want to keep warm all night long. The key is keeping it under your body so that your body heat warms up the inside just like with earth insulation.
Seal out drafts: A windproof bivvy sack will help minimize drafts, but there are still times when cold air will infiltrate even the best bivvy sacks. If you feel cold air hitting your nose, find the source of it and fix it.
Do not get out of the bivvy sack too often: Getting out even once every two hours to either urinate or move around will make it harder for you to stay warm all night long. If you have a bivvy sack that is not completely windproof, this will make you lose body heat much faster.
Keep vital gear inside the bivvy sack: Your pack makes a good pillow and a bad insulator. If your boots or anything else that’s useful is inside your sleeping bag with you then it’ll be warmer. And more comfortable too!
Inspect your feet: In extremely cold weather, frostbite on one’s extremities can become an issue. Keep an eye out for any changes in color or temperature of your hands, nose, ears and feet while outside in the cold all day long and fix any problems immediately upon returning to camp. This can save you from some serious pain later on.
Be prepared to pack up quickly: There’s a reason why experienced bivvyers make sure every piece of their campsite is packed away before going to bed. It takes less than five minutes from the moment you hear raindrops hitting your canopy to waking up soaking wet and cold, the bottom half of your sleeping bag full of water. In an emergency situation, consider working on getting your sleeping insulation dry while you put it all into a stuff sack to keep it safe and dry if there’s no time for digging through your backpack in the dark.
Bring enough food and water: Without something warm to drink or food in our stomachs we’ll feel miserable very fast – even when wrapped inside two sleeping bags with four layers on. Keep emergency rations inside your sleeping bag all night long for quick access in case you can’t get things ready quickly enough.
Sleeping inside a bivvy bag is the most effective way to stay warm during cold-weather camping trips. Just remember to take extra precautions before meeting any weather extremes, and always be prepared to pack up if the weather turns ugly all of a sudden.
Always bring extra water than you think necessary because dehydration makes it much harder to keep warm by lowering your metabolism.
And finally, eat lots of high calorie food before bedtime so that you’ll have plenty of body heat stored away after dark!