Answer Question
If you're going to be sleeping in 0F degree weather, then a -20F degree down sleeping bag would be advised. Anything colder, you should consider getting a -40 degree sleeping bag for winter camping.
Here are some really good down winter sleeping bags rated at least -20F (-28C)
Here are some super warm winter sleeping bags rated -40F (-40C)
Also two of the best sleeping pads to keep you warm when sleeping on cold surfaces in the winter are the Therm-a-Rest Z Lite Sol Mattress along with the Therm-a-Rest Neo-Air Xtherm Sleeping Pad.
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