This is a good bag. I spent a two weeks in colorado in december 2012 , temps were anywhere from 20 to -20 and it was toasty. the -40 is an absolute limit meaning that is the coldest temp that it will keep you alive. its comfort limit is probably around -20 or -30 degrees. Great bag for the price and since it is synthetic not down, it should stay warm if wet. If you will not be using it below -10 I would get the North Face Dark Star -20 synthetic which performs great at -10 to 0 degree range. Hope that helps you!