Took this on a Spring Bear hunt in Montana during April. While turning in for the night I felt some precipitation and closed it up. When I awoke and had to respond to nature's call, I unzipped the opening to find everything was blanketed in white as it had snowed. I promptly changed my plans, re-zipped up the flap and went back to sleep. When I got up the next morning, I had ZERO condensation! Highly impressed with the breathability of this material and I really prefer the opening on the top as opposed to the type you have to shimmy into from the end. All in all, Great bivy!!!