A selectively openable and closable, outdoor storage bag includes a body portion made of a flexible, waterproof, plastic coated fabric bag material, the bag material comprising a plurality of waterproof welded seams that define a predetermined shape of the body portion and an opening, the body portion defining an interior space within the body portion; a closure mechanism joined to the body portion by a welded seam proximate a periphery of the opening, the closure mechanism configured to selectively open and close the opening and provide a seal that is at least water-resistant when the opening is closed; a flap of the plastic coated fabric bag material that extends from the body portion and covers the closure mechanism; and a plurality of anchor points attached to an exterior surface of the body portion, wherein the body portion of the bag is waterproof and the seal is at least water-resistant.