In most of African countries whose economy is heavily depending on rain fed agriculture, so Ethiopia’s economy is mainly dependent on rain-fed agriculture, the failure or the goodness of seasonal rainfall is very important to the country’s socio economic functioning- in particular, food production and for water resource. As a result, the reliable seasonal rainfall prediction would have several advantages for agricultural activities, water management, health and increasing the frequency of extreme prolonged events such as drought and floods at local and transboundary. In this paper, an attempt is made to study the predictability and variability of rainfall over Blue Nile basin during two rainy seasons using statistical methods Mann Kendall analysis technique with standard rainfall statistical descriptors. Where the technic is a statistical test widely used for analyzing trends in climatologic and hydrologic time-series. In this study we examines the spatial and temporal rainfall characteristics of upper Blue Nile river basin of four meteorological stations with 33 years of daily rainfall data and monthly have been used. In this case, the climatology over the stations vary 1059 to 1427.5mm. With respect to the main wet seasons, the June–September precipitation has strong connection with neighboring ocean basins. The spring rainfall variability is strongly linked to sea level pressure over Pacific and most parts of Indian Ocean. Belg (“small rainfall” in March – May) rain makes a considerable contribution to the annual total to Kombolcha but little contribution around Debre Markos region. Annual rainfall has shown negative and positive anomalies for much of the 1980’s and 1990’s, respectively. Heavy and deficiency rainfall is frequent occurred at stations due to local factors, which are relatively close to the lake and any linkages to large-scale ocean–atmosphere effect of climate change.