The historical rainfall data for the period of 22 years (19981-2019) of Samastipur district in Bihar were analyzed weekly rainfall data by using Markov chain model and initial and conditional probabilities were estimated for 10 mm and 20 mm rainfall amount. the initial probability of getting 10 mm rainfall during 23th to 42th SMW are more than 60% except 39th,41th and 42th SMW. | Weekly rainfall analysis by markov chain model in Samastipur district of Bihar India