Using 100 years of weekly rainfall data for Baharampur, profile moisture at sowing were simulated for coarse, medium and fine textured soils for six different sowing weeks starting from 38th (Sep 17 – 23) standard meteorological week (SMW) at two weeks interval and associated climatic risk was quantified using climatological water balance approach for yellow sarson, an important rainfed rabi crop of West Bengal. Same database was also used to run a FAO crop specific water balance model at weekly time steps to assess model outputs for Binoy variety. Yield prospects were estimated from water requirement satisfaction index (WRSI). At least 100 mm moisture is present to start sowing upto 42nd and 46th SMW in medium and fine textured soil respectively, at 75 percent probability level, for good initial growth of the plant. At least mediocre crop yield, in every alternate year, is possible when sown upto 40th SMW in medium and upto 44th SMW in fine textured soil. Prospect of getting good yield exist in more than 20 percent of the year if sown within 7th October in fine textured soil.