Rainfall Climatology and Variability in Ethiopian Airports

Understanding rainfall characteristic is very important for aviation operational planning and for other activities. This study investigated annual, seasonal and monthly rainfall climatology and variability in Ethiopian Active airports from 1991-1994 using time series Climate Hazards Group Infrared Precipitation with Stations (CHIRPS) rainfall datasets. Long year mean, standard deviation and coefficient of variations were used to analyze Annual, Monthly and seasonal rainfall climatology and variability spatially and on active airports as a point. Western and southwestern airports such as Jimma, Asosa, Bahir Dar, and Gambella exhibit the highest annual mean rainfall, consistently exceeding 1,200mm, while eastern and northeastern Airports like Gode and Semera, experience very low annual totals (often below 300mm. For instance, Jimma airport records monthly averages exceeding 200mm in peak months, while Airports like Axum, Humera, and Gode receive less than 1mm in dry months. The Kiremt season contributes the bulk of annual rainfall in most parts of the country, for instance Nekemte Airport (1324.5mm), Bahir Dar airport (1147.4mm), and Jimma airport (881.0mm) leading as high climatological mean rainfall. Belg (February-May) and Bega (October-January) are secondary rainfall seasons and dry seasons respectively but are significant in southern and southwestern parts of the country such as Jinka and Arba Minch. More than 80% of airports fall under low annual rainfall variability (CV < 20%), indicating high reliability for long-term aviation planning. Only Gode airport shows high annual rainfall variability (CV = 41%), indicating operational unpredictability and risk exposure. CV values during dry months often exceed 200%, particularly in arid and semi-arid regions, indicating unreliable rainfall patterns. In contrast, wet months (July-August) in western airports exhibit low CVs (e.g., Bahir Dar: 11.8% in August), supporting predictable seasonal operations. Generally climatological and variability insights highlight the spatial and temporal heterogeneity of rainfall across Ethiopian airports, driven by topography, regional climate systems, and global drivers like ENSO. Understanding both average conditions (climatology) and year-to-year fluctuations (variability) is critical for aviation safety, infrastructure resilience, and operational efficiency.