An installable window protector, for protecting windows against flying debris incident to severe storms is provided for metal extrusion frame windows. A rectangular sheet of plywood, sized to the internal dimensions of the window frame, is provided with two, vertically in line handles in the lower third section to permit the entire sheet to be readily twisted and manipulated by an individual standing within the window. The end of the sheet opposite to the location of the handles is provided with a tapered edge and at a location approximately at a lower third dividing line of the sheet two opposed extendable deadbolts are installed. The sheet is easily installed to cover the exterior of the window by a person standing in the house, by opening the window and manipulating the sheet by means of holding both handles so as to pass the sheet to the outside of the window. The sheet then may be readily engaged with the top lip of the metal window frame, the taper serving to guide the sheet into place. The sheet is then pulled snug against the window frame and secured by means of extending the left and right deadbolts. Cooperating holes may be provided within the metal frame to further engage the deadbolts. The sheet provides a tight fitting cover, resistant to tampering from the outside, and providing suitable flying debris and other impact protection for the windows.