I have found the material on my Caribou to be very water resistant. The first time out with it I was car camping with my motorcycle and got some light rain over night. I felt a little clammy and in the morning, water was puddled up on top of the bag. I now can see light thru the stitching, so I don't know if it could hold off the water again. I have had that WM bag for five years now I think. My Apache has been good down to 15 like it's rating, but just barely, and a couple years ago, I had heavy condensation inside my floorless, Tarptent Squall in the Fall and I felt cool in the bag for some reason. Not a conservative rating for the Apache has been by experience.