Spent two weeks sleeping comfortably in 30 degree weather. I never once felt the chills and most nights never even had to zip up all the way. Granted, I am a very warm sleeper, but I would take this bag down to 20 degrees with very little problems. Western Mountaineering makes a no frills (and no chills) bag that will last a lifetime as long as you take care of it like it takes care of you. The price is steep, but it might be the last bag you ever buy (or, if you are like me, just the first in the entire WM lineup). Add to all that the fact that it is Made in America and you should feel very warm about your WM purchase.