Abstract: An air deflection system for a snow plow assembly mounted on a vehicle comprises an air stream guide member mounted on and overlying the upper surface of a snow plow blade. The guide member has a downwardly facing air inlet at a fore end positioned forward of the snow plow blade to intercept and capture without interruption an air stream which, by reason of forward movement of the vehicle, is directed toward the leading concave surface of the snow plow blade, then upwardly along that surface, and through a rearwardly facing air outlet at the aft end positioned aft of the snowplow blade. An air stream containment passage intermediate the air inlet and the air outlet is effective to receive the air stream from the air inlet and redirect it toward the air outlet from whence it is exhausted away from the snow plow blade and toward the radiator of the motor vehicle.