Abstract: A roadside warning sign system including sign support comprised of a housing having a top wall, a bottom wall, opposed side walls, an open front face, and an open back face. The housing has a light source disposed interiorly thereof. The light source has a power source. A plurality of signs are provided that are each couplable with the open front and rear faces of the housing of the sign support. The signs each have indicia thereon corresponding with vehicle problems or hazardous conditions. The signs are translucent. A base portion is provided that is adapted for coupling with a roof of a vehicle. The base portion is comprised of a lower horizontal member having an upper surface and a lower surface. The base portion includes a pair of side brackets extending upwardly from the upper surface of the lower horizontal member. The side brackets secure the sign support to the base portion.