This past summer of camping rentals was eye opening to me regarding people's expectations of sleeping bags, or maybe it had more to do with people's expectations of summer camping. Elsewhere in the US summer camping consists of fairly warm, reliable weather, even if it can be rainy and wet in some areas. However, the Rocky Mountains have extremely variable weather most of the year and it can snow at any time. Our daily temperature swings can be extreme going from 70 or 80 degrees F to freezing temperatures. I found our renters who brought their own sleeping bags were often cold and uncomfortable.
My goal with this post is to shed a little light on the options available when buying a sleeping bag and how to choose a sleeping bag for overlanding or car camping. As you become more experienced you will find a setup which works well for you in the climates you routinely camp in.
The first step to selecting a proper sleeping bag is to determine your intended use. I know I said this post is about car camping, but often car campers are also backpackers, bikers, hunters or some other recreational enthusiast. It can be a good idea to determine all your sleeping bag needs and buy one to fit them all if possible. The difference between bags for different uses will be weight, warmth and cost. Warmer, and lighter usually equal a higher price.
Don't let yourself get pigeonholed into sleeping bags marketed for your specific activity. There are some great products marketed to different sports which may have the perfect product for you such as hunting sleeping bags (usually really warm and cozy) or ultralight quilts (my preferred method which keeps me warm and able to move at night).
Determining the temperature rating of the sleeping bag you need will help you narrow down options. To me this is a non-negotiable spec of any sleeping bag I buy. If you will be car camping in winter then you will want a bag rated well below your expected lowest temperature. If you only camp in the hot summer months you can get away with a much warmer rated bag. In my experience the listed temperature ratings on bags are the point at which you will not die of hypothermia - not the temperature at which you will be comfortable! This is why I use a 20 degree F bag even in the summer.
Sleeping bags are usually rated between 15 and 50 degrees F. I would never buy a 50 degree bag to use in Montana as the nights are generally going to be colder than that in the mountains - the highest I would buy is 35 degrees F. If you want a really cold bag you can find them rated as low as -40 degrees F designed for mountaineering, anything below 0 degrees F is probably overkill for most people!
Here is a breakdown of suggested temperatures from REI:
There are two main types of insulation in sleeping bags. Down and synthetic which is generally made of polyester. Down is great for cold, dry weather as once the down gets wet it looses insulating power. However, down gives more warmth for the weight. Synthetic performs well in warmer and wetter conditions. If synthetic bags get wet they still keep you insulated. Synthetic bags are generally cheaper than down bags and a typical car camping sleeping bag will only be offered in synthetic. Either option is good for Montana since we are dry most of the year. Down bags seem to regulate temperature well even in the summer, but they may be too warm for hot sleepers. Down will also pack down smaller than synthetic bags if you are also hoping to use it backpacking.
When shopping in a sporting goods store you will notice there are different shaped sleeping bags. Usually the choice is between rectangular or "mummy" style bags. In my experience rectangular bags are much more comfortable than mummy bags as there is room to move. However, you will miss out on the hood which can help conserve heat and there is greater space for you to heat. Mummy bags will be lighter weight as they have less material.
Weight and Size
In general weight and size doesn't factor into car camping too much. This is more of a concern for backpacking or other sports where you need to carry your bag and you have limited space. However, it is worth thinking about especially if you have a small car or a spot you want them to fit (for example: storage inside a roof top tent). Rectangular, synthetic bags of a low temperature rating will be the largest and heaviest bags. Mummy bags made of down will be the smallest and lightest bags.
There are a few alternatives to buying a sleeping bag. The obvious is using blankets and other types of home bedding. These options can work well, but it is hard to find ones warm enough. Usually a house is at least 60 degrees F at night where outside could be much lower.
Outdoor blankets are making waves right now, the main brand being Rumpl. The lowest rating I have found on these is 45 degrees F, which as I have stated above, just isn't warm enough to use alone in Montana. Some of these blankets rival the cost of a sleeping bag as well. Pair one of these with a fleece blanket and it could be a great option for overlanding and car camping.
Another option which is a bit newer to the sleeping bag world is a quilt. These were created for ultralight weight backpacking and are kind of like a sleeping bag, but generally do not have a zipper or hood in order to reduce weight. They are also designed to go over you and not under (you don't lay on any part of the quilt).
My husband and I started using these in our roof top tent for a few reasons:
I recommend the average car camper buy a synthetic, rectangular bag, but look carefully at construction and temperature rating. I find hunting bags are some of the best ones out there. They are made of heavy duty material and have colder ratings than some of the typical bags you will find. Their downside is they can be big and bulky. Regardless of the type you determine is right for you, buy from a sporting goods store as they will have well-made products from good brands. In my area REI and Sportsman's Warehouse have good products. Just like everything else you get what you pay for so stay away from sleeping bags offered at Wal-Mart and similar stores! They will be rated for very warm temperatures and they don't hold up well.
Amy Bowser is the co-owner of Paradise Overland with her husband Jon. In their free time they explore anywhere they can get to with their Toyota and roof top tent.