An adjustable curtain mounting assembly covers a window assembly and comprises a mounting plate adapted to be attachable to the window assembly, a backer, and a first attachment element releasably attaching the backer to the mounting plate, a curtain attachable to the window assembly, and a cover having a second attachment element releasably attaching the cover to the backer. The backer is positioned between the cover and the mounting plate, and the curtain is positioned between the cover and the backer, and the cover, the backer and the mounting plate area cooperate to resist relative movement of the curtain with respect to the window assembly.