What are the Best Sleeping Bags for very cold weather?

The best sleeping bag you choose for cold weather camping will depend on when you plan to camp and how cold you sleep.  For cold weather winter camping, it would be best to have at least a -20 Sleeping Bag to be safe.  If you're faced with really extreme temperatures, you can use layers to supplement the sleeping bag. If you're using the sleeping bag for mountaineering, you may need an even colder rated sleeping bag (-30 to -40).  It's usually a good idea to get a sleeping bag rated to handle 15 degrees colder than tempatures you expect to experience while camping in order to be sure you will remain warm enough.

Here are some of the best sleeping bags for cold weather rated to at least -20F (-28C) 

• Feathered Friends Ptarmigan EX -25 Degree Down Sleeping Bag
• Western Mountaineering Puma Gore WS -25 Degree Down Sleeping Bag
• Mountain Hardwear Wraith -20°F Degree Down Sleeping Bag
• REI Expedition -20 Degree Down Sleeping Bag
• Marmot Col MemBrain -20 Degree Sleeping Bag

Here are some of the best sleeping bags for extreme weather rated to at least -30F (-34C) 

• Marmot CWM Membrain -40 Degree Sleeping Bag
• Feathered Friends Snow Goose EX -40 Degree Sleeping Bag
• Western Mountaineering Bison GWS -40 Degree Sleeping Bag
• Mountain Hardware Ghost -40 Degree Sleeping Bag

The best cold weather sleeping bags should be:

• Down Only. Synthetic bags are not acceptable due to their size and weight.
• Sleeping bag needs to be a mummy-style down bag rated between minus -20°F and -40°F.
• Many people are happy with a -20°F bag, but if you sleep cold you'll want a warmer bag.
• The temperature rating system for sleeping bags is arbitrary and is not a guarantee of warmth.
• Base your selection on how well you do in the cold. If you tend to sleep on the cold side, choose a bag rated on the lower end of the temperature range.
• Unless you are shorter than 5’ 8”, the long version is better to accommodate all the items you need to sleep with: 2 water bottles, liner boots, any thing else that needs to dry out.
• If you need extra insulation to sleep warm, you can wear your overpants and wear your parka in your sleeping bag.