User Review: The North Face Dark Star -40
Fill: Polarguard HV
Temperature Rating: -40 F
Price Paid: $250
I recently was camped for a few nights in the Boundary Waters Wilderness here in northeastern Minnesota with temps down to a moderately cold -31 F. I slept plenty warm in the Dark Star, and the -40 F rating seems reasonable. It's probably too warm for temps above about 10 F.
Another review raved about this bag for cold, wet conditions, but if its wet outside, the temp is way too warm for this bag.
The drift collar adjustment is a bit weird though and takes some getting used to. I prefer a traditional toggle-lock. The bag is of typical bulk for a true cold weather synthetic bag.
Like with any winter sleeping bag, a warm night's sleep in truly cold conditions requires a good, thick sleeping pad, a fleece hat, and perhaps a down vest wrapped around the feet to fill extra space in the foot of the bag.