Spatiotemporal variability and trends in rainfall and temperature in the central highlands of Ethiopia

This study investigates the spatiotemporal variability and trends of rainfall and temperature in the Ejerie district, Ethiopia, focusing on the Dega and Weyina Dega agroecological zones. Gridded monthly rainfall data (1990–2020) and temperature records (1990–2018) from the Ethiopian Meteorology Institute were analyzed at a 4 × 4 km resolution. Variability was assessed using mean, standard deviation, coefficient of variation (CV), precipitation concentration index (PCI), and standardized rainfall anomaly (SRA). Trend analysis was conducted using the Mann–Kendall test (MK test) and innovative trend analysis (ITA). Results showed that Dega receives 1245 mm of annual rainfall, while Weyina Dega receives 907.8 mm, with both regions exhibiting low rainfall variability. Rainfall is concentrated in the summer season, followed by Belg and Bega, with notable monthly variability in November and December. The PCI analysis indicated irregular rainfall distributions, with Dega showing 87.09% irregular and 9.68% strongly irregular distributions, while Weyina Dega showed 83.87% irregular and 3.23% strongly irregular distributions. SRA analysis revealed that 83.27% of Dega and 84.48% of Weyina Dega did not experience drought, with minor drought occurrences observed in both regions. Temperature analysis showed significant seasonal differences, with Dega experiencing cooler temperatures than Weyina Dega, which has a warmer climate. Both the MK test and ITA methods yielded consistent temperature trends, with the exception of minor discrepancies in Bega season temperatures. These findings emphasize the importance of localized climate studies to inform area-specific adaptation strategies for agriculture and water resource management in the region.