A bin lid assembly includes a lid member arranged to span across an opening in the roof of a grain storage bin. The lid member is supported by a hinge which is biased towards a closed position extending forwardly across the bin opening from an open position extending rearwardly. An operating linkage is pivotally connected to the lid member and includes a opening arm which is folded relative to the lid member from a first position extending upwardly in the closed position of the lid member to a second position extending rearwardly in the open position of the lid member to allow the lid member to be opened 180 degrees. The linkage also allows a mechanical advantage to be maintained when pulling the lid open using an actuator tether alongside the bin which is connected at an upper end to the opening arm.