Yes they are designed to be used in the rain. When it comes to waterproofing in backpacks it’s all about creating layers. Our backpacks are currently protected by the following layers:   1. Wax Coating 2. Hood Design Creates 2 additional layers at the top of the bag 3. Main Fabric Cotna 900d with a waterproof backing 4. Lining Nylon 210d with a waterproof backing   Our Mainpack comes with a  Flight & Rain cover to create additional layer of Nylon 210d with a waterproof backing.   Look at our additional information about the Flight & Rain cover here.