How do I seal this grating when it rains?
If you have no glass to keep rain out and the window is open all year except when you put plastic over it. If you prefer to have no glass, I am sure there is a producer of automatic louvers that have a rain sensor to sense when they need to close. They may shade the window more than the grate does now, but it will keep the rain out.I am sure the shade will be custom made for each window.