Smadhi, D.Zella, L.Bachir, H.2020-11-052020-11-052017-05-01Articale in Journal of fundamental and Applied Sciences Vol. 09, N. 021112-9867http://dspace.univ-eloued.dz/handle/123456789/7412Articale in Journal of fundamental and Applied Sciences Vol. 09, N. 02The droughts in the semi-arid Algeria’s cereal regions are evaluated by studying the average monthly rainfall, from September to June, over the period (1941-2011), based on the first-order Markov chain. This method traces rainy and dry days, cumulative rainfall and the probability of receiving rainfall above the thresholds of 0,1, 5, 10, 20 and 30 mm, in conjunction with the cereal development cycle. The rains analysed showed that the distribution of rainy days at the chosen thresholds did not exceed the variable averages of 6 to 9 days per month. These days are characterized by random cumulative rainfall, with probabilities fluctuating between + 40% and + 80%. Hard droughts affect seeding dates and yield factors for rainfed cereals.frAlgeria, rainfall, Sowing, Markov Chain.Article