Best kind of removable window well covers

I recently installed a window well cover over my one window well because we have been having sooo much rain. Though the window did not leak, the base of the floor below the window became saturated and I suspect that the well filled with water and directed the water down the outside wall causing at least in part to the wall to become too wet and seeping through. But now that I have the window cover installed I can no longer use that window for ventilation and that creates a different problem. Is there a window well cover that are designed to be removable so that the window is still usable in dry weather? Of course the one that I have can be unscrewed but is really not designed to be taken on and off regularly.