Last winter I spent most of my nights sleeping outside in a hammock. This may sound cold, but it really was not.
This hammock is 3m wide and 2.5m when the ropes are not installed, and has slept three people comfortably. The liner is thick fleece fun fur. The shell is coated rain wear nylon, which is both wind and water proof. With the tarp and everything tethered properly it is ready for any weather except extreme heat.
I also have two fun fur blankets that I use as the temperature gets lower. I have gotten to almost -20 degrees Celsius with just two fun fur blankets and some warm clothing, and about zero with almost nothing in addition to the blankets.
There are zippers on the ends so that the foot end of the hammock can be zipped up to both keep the blanket inside the hammock around the feet, and keep the hammock closed by the feet.
In a pinch the hammock can be used as a warm sleeping bag on the ground as well. This year when I took this hammock to Evolve I did not actually get to sleep in it because it was always occupied by someone else who was sleeping. I only hear good things about the comfort and warmth.