Spatiotemporal variability and trends in extreme rainfall and temperature indices in Southeastern Oromia, Ethiopia

Extreme climatic events have become a significant global concern, exacerbating drought and flood risks in Ethiopia's agricultural regions. This study presents the first multi-index analysis of 23 ETCCDI indices in southeastern Oromia (1994-2023) to address hydrological challenges. Using data from nine meteorological stations, we analyzed spatiotemporal trends via the Modified Mann-Kendall test with Hamed and Rao's autocorrelation correction, Theil-Sen slope estimator, descriptive statistics, linear regression, and Standardized Anomaly Index (SAI). Spatial interpolation employed Inverse Distance Weighting (IDW). The results show that the rainfall extremes (CWD, R20mm, R25mm) and temperature indices (TNn, SU25, CSDI, WSDI) exhibited high variability (CV > 30%). Significant declines occurred in RX1day, R95p, and R99p, while CDD increased by + 0.4 to + 1.17 days/year at 77.8% of stations. Warming trends dominated: TX90p and TN90p rose by 0.10 to 0.57 and 0.20 to 0.60 days/year, respectively; TXx and TNx increased by 0.03 to 0.2 °C/year and 0.05 to 0.12 °C/year at all stations. All stations showed rising TXx, TNx, TX90p, and TN90p, with 66.7% recording more SU days. Hot indices (TXx, TNx, TX90p, TN90p, SU) increased as cold indices (TNn, TXn, TX10p, TN10p) declined, highlighting warming asymmetry. Spatial analysis revealed station-specific variability, emphasizing localized climate risks. These trends demand urgent adaptive strategies to mitigate escalating climate threats in vulnerable regions.