The device has a transparent rubber sheet (1). This can be pulled over the outside of the roof window and its flashings. The sheet is profiled on both sides to cause the rain to run off and avoid a vacuum sticking the underside of the sheet to the window glass. One end of the rubber sheet is held on a roller (2). The other has an opening through which an adjustable length rod (5) can be pushed. The rod is pulled across in guides by a chord (8) from inside the room to cover the window with the sheet.
