The surface-referenced algorithm, referred as kZS, performs at its best when uncertainty related to sea surface normalized radar cross section (NRCS) is limited. The kZS algorithm is upgraded based on the prediction of the NRCS of the water surface roughened by both wind and rainfall. Such prediction relies on the full wave model (FWM). Improved performance of the rainfall profile retrieval scheme is demonstrated via simulations carried out at 13.75 GHz for different rainfall rates over the sea surface and different rainfall profiles. All of them showed that the rainfall profile retrieval accuracy can greatly benefit from a more accurate prediction of NRCS.