Summer might bring mild weather, but it also brings crowded trails, so we use frigid temps to our advantage and head to the mountains with Marmot's Never Summer 0 Degree Down Sleeping Bag in winter weather. Stuffed full of Marmot's water-resistant Down Defender 650-fill down, the Never Summer keeps us warm when temperatures drop to single digits, and its DWR coating adds a bit more protection from light snow flurries that might accumulate along the walls of the tent.