Rainfall Characterization over Western Amhara, Ethiopia

Climate change has intensified rainfall variability across Sub-Saharan Africa, posing significant threats to smallholder farmers who rely on rain-fed agriculture for their livelihoods. Ethiopia, and particularly the Amhara region, is among the most vulnerable areas due to its dependence on seasonal rainfall and diverse topography. Despite numerous studies, findings on rainfall variability across Ethiopia remain inconsistent, underscoring the need for localized assessments. This study investigates rainfall characterization in western Amhara, Ethiopia, focusing on onset, cessation, length of growing period (LGP), and variability over the period 1992–2021. Data from 11 meteorological stations were analyzed using the Climate Data Tool (CDT), supported by quality control methods to address missing values, outliers, and homogeneity issues. The results indicate that the mean rainfall onset in western Amhara occurs on May 28 (Day of Year 148), with early and late onsets ranging between May 3 and June 30. The mean cessation date is September 29 (Day of Year 272), varying from July 14 to October 15 across stations. Consequently, the mean LGP is 124 days, with ranges from 103 to 151 days, reflecting both interannual and spatial variability. Stability analysis revealed high consistency in onset and LGP (standard deviations of 11 and 13 days, respectively) and very high stability in cessation dates (SD = 4 days). Annual total rainfall ranged between 995 mm and 1783.5 mm, with a mean of 1316.7 mm and coefficient of variation (CV) of 14.4%. Seasonal Kiremt rainfall averaged 1002 mm, with CV values of 15.6%, highlighting moderate variability. Compared to previous studies, this research observed shorter growing periods, pointing to emerging challenges for crop production under shifting climatic conditions. The study emphasizes the importance of localized rainfall analysis for agricultural planning, food security, and climate adaptation. Findings provide critical insights for farmers in timing planting and harvesting, while also supporting policymakers in designing targeted interventions for resilience. It is recommended that future work expand the network of meteorological stations, enhance community-based monitoring, and foster interdisciplinary collaboration to improve adaptation strategies. Ultimately, understanding rainfall dynamics in western Amhara is essential for ensuring sustainable agricultural productivity and resilience in the face of climate variability.