Long-term trends and characterization of temperature and precipitation over Southwest Ethiopia and their hydro-climatic event implications

Climate variability is a significant driver of global change and a threat to societies worldwide. Learning from past climatic patterns provides the foundation for building a resilient and sustainable future. This study delivers a rigorous analysis of climate variability and trends in Jimma City, Southwest Ethiopia. Employing different statistical metrics and robust non-parametric methods, the Modified Mann-Kendall (MMK) test, Sen’s Slope Estimator (SSE), and Innovative Trend Analysis (ITA), this study quantified significant climatic shifts. The variability test results showed clear divergence between the precipitation and temperature data. Annual precipitation is characterized by low variability (CV < 20) and a moderate distribution (PCI < 15). Conversely, seasonal rainfall was highly variable and irregular. Temperature data across all annual and seasonal scales showed a very low variability (< 10). The standardized anomaly index (SAI) for both variables fell primarily within the near-normal range; however, several annual instances were also registered in the severe and extreme categories. The precipitation showed predominantly increasing trends across all stations and seasons. For Jimma station, the annual and Belg season trends are statistically significant (p value < 0.05), with Sen’s slopes of 8.00 and 3.09 mm/year, respectively. A notable exception is the Bega season in Yebu, where the ITA indicates a decreasing trend (Ꝋ = − 0.659), in contrast to MMK’s non-significant increase. The temperature trends increase universally. Most MMK trends were not statistically significant except for Serbo’s annual (Z = 3.55, p = 0.003), Kiremt (Z = 6.34, p = 0.000), and Yebu’s Bega seasons (Z = 4.979, p = 0.006), which show strong significant warming. The ITA results (all positive Ꝋ values) confirm this consistent warming signal across all locations and timescales. The findings reveal variability, a warming trend, and predominantly increasing precipitation patterns over the city. To mitigate risks from future hydro-climatic extremes, local planners should integrate adaptive water management and climate-resilient urban development strategies.