A wind deflector assembly for a roll tarping system mounted on a vehicle includes a pair of side mounting plates, each associated with a corresponding opposite end of the roll tarping system. Each of the mounting plates includes a first edge and at least one flange projecting from a notch formed in the first edge of the mounting plate. An elongated deflector plate includes at least one variable location mounting element defined on an inner surface thereof. Each mounting element is arranged to be aligned with a corresponding flange when the deflector plate is mounted to the side mounting plates. The flange includes a fastener opening, while the mounting element includes a T-slot and channel. At least two fasteners are provided for connecting the deflector plate to each side mounting plate. The fastener can include a bolt sized to slide within the T-slot and channel, and a nut that is threaded onto the bolt when it extends from the mounting element through the opening in the flanges. The deflector plate is provided in a length that is greater than the necessary width to cover the tarping system. The deflector plate is cut to length during installation.