The study shows the factors affecting rain precipitation, general rate and annual, monthly and daily changes by calculating the standard deviation and the annual fluctuation. The standard deviation from the general average shows large values in the stations located in the north of the study area. Stations in the center and south, because of the nature of the dry climate, as well as that the increase in the number of rainy days does not necessarily mean an increase in the amount of precipitation, and a difference in the amount of rainfall from one station to another because of the difference in climatic factors affecting them .