Ethiopia, a densely populated country with abundant natural resources, is often hit by climate extreme disasters that cause severe damage to life and property every year in one or the other corner. The frequency and intensity of extreme events have increased in the recent decades due to climate change and variability. This study aimed to analyze the changes in observed rainfall and minimum and maximum temperature extremes in the Upper Blue Nile Basin (UBNB) of Ethiopia from 1980 to 2019 periods. The Mann-Kendall (MK) trend test and Theil-Sen's slope estimator were used to estimate annual and seasonal trends. The rainfall and temperature extremes were analyzed using RClimDex, which is a graphical user interface in R software, by selecting ten rainfall and eleven temperature indices. The results showed a positive trend in annual, dry (March–May) and small rain (October–February) seasons rainfall in more than 54% of the stations and a decreasing trend in the main rain (June–September) season rainfall in 65.4% of the stations. Several extreme rainfall indices showed insignificant positive trends in the basin. Although there is a positive trend in extreme rainfall, the number of consecutive wet days (CWD) and the simple daily intensity index (SDII) show insignificant negative trends in most stations. In addition, a warming trend of the annual and seasonal maximum and minimum temperature extreme indices was noted. Overall, the increase in extreme rainfall and a warming trend in the extreme temperature indices indicate signs of climate change in the UBNB. The findings of this study suggests the need for developing climate change adaptation and mitigation strategies in the UBNB.

埃塞俄比亚是一个人口稠密、自然资源丰富的国家，每年都会在一个或另一个角落遭受气候极端灾害的侵袭，对生命财产造成严重破坏。近几十年来，由于气候变化和多变性，极端事件的频率和强度有所增加。本研究旨在分析 1980 年至 2019 年期间埃塞俄比亚上青尼罗河盆地 (UBNB) 观测到的降雨量以及最低和最高极端温度的变化。Mann-Kendall (MK) 趋势检验和 Theil-Sen 斜率估计器用于估计年度和季节性趋势。使用 R 软件中的图形用户界面 RClimDex 通过选择 10 个降雨和 11 个温度指数来分析降雨和极端温度。结果显示，年均呈积极趋势，旱季（3-5 月）和小雨季（10-2 月）降雨量超过 54% 的站点，主雨季（6-9 月）降雨量在 65.4% 的站点呈下降趋势。几个极端降雨指数在流域内显示出微不足道的积极趋势。虽然极端降雨量呈正趋势，但大多数站点的连续雨天数（CWD）和简单日强度指数（SDII）均呈现出微不足道的负趋势。此外，还注意到年度和季节最高和最低温度极端指数的变暖趋势。总体而言，极端降雨的增加和极端温度指数的变暖趋势表明 UBNB 有气候变化的迹象。这项研究的结果表明，有必要在 UBNB 中制定气候变化适应和缓解战略。