Changes in wet and dry patterns have an impact on rain-fed agriculture in Eastern Africa, mainly Ethiopia due to high venerability to climate variability. This study aimed to characterize number of rainy days and the probability of different dry spell length. The result showed high temporal and spatial variation of rainy days for all season. Moreover, belg (FMAM) and Kiremt(JJAS) rainy days exhibited inconsistent spatial trend. At all stations on the average probability weekend dry spell was greater than 40% February to end of September. Similarly, at Asebe Teferi and Mieso decadal dry spell was risky (>50%) during the entire belg season. However, at remaining stations not risky in the month of April and May. Probability of decadal dry spell was risky from end of 1st decade of September to end at Asebe Teferi, Hirna and Mieso and also after end of 2nd decade of September at Bedesa. Therefore, for the identified dry spell risky period and crops whose cycle extends to October; farmers should get access to irrigation and other mechanisms that minimize the loss of moisture from the farm land.

Keywords: Asebe Teferi, Bedesa, Belg, Hirna, Kiremt, Mechara, Mieso, number of rainy days, probability of dry spell length