A grain storage pit includes an open-top chamber configured to be substantially flush-mounted in a surface and a grain-receiving grate that covers at least a portion of the open-top chamber so that grain may be poured into the open-top chamber through the grate from a truck positioned over the pit. The grate has a convex-shaped upper surface so that a cover placed over the grate more effectively sheds water. The grain storage pit may also include one or more unloading ports for facilitating removal of grain from the pit. At least one of the unloading ports may be adjustably mounted to an opening in the chamber.