limate change is a worldwide concern that poses a treat of the century and has resulted in significant damages. Projection as well as identification of past and future changes in climatextremes is important. The study aimed to assess CMIP6 climate model performances and projections of climate extreme indices over the Upper Blue Nile Basin, Northwestern Ethiopia.Observed and future CMIP6 precipitation and temperature data under SSP1-2.6, SSP2-4.5, and SSP5-8.5 for near (2015-2044), mid (2045-2074) and far (2075-2100) periods were used. Thestudy was applied power transformation and distribution mapping for precipitation andtemperature bias correction methods to correct the bias of seven CMIP6 models, respectively. To alidate the performance of model data with observed data, the statistical evaluation techniques ere employed. Mann–Kendall (MK) and Sen’s slope tests were computed to detect the rainfalland temperature trends and magnitude of change, respectively. Furthermore, the spatiotemporadistribution and trends of 15 extreme indices from the ETCCDI list were computed. Theperformance evaluation result revealed that model INM-CM5-0 and INM-CM4-8 for precipitation and temperature were selected based on their highest performance, respectively. The precipitation projection in all agro-climatic zones under SSP1-2.6, SSP2-4.5, and SSP5-8.5 scenarios showsignificant (p<0.01) positive trend. The mean annual maximum temperature over UBNB isprojected to increase by 1.8°C, 2.1°C, and 2.8 °C under SSP1-2.6, SSP2-4.5, and SSP5-8.5 from 2015-2100, respectively. Similarly, the mean annual minimum temperature is estimated toincrease by 1.5°C, 2.1°C, and 3.1 °C under SSP1-2.6, SSP2-4.5, and SSP5-8.5, respectively. Thending also reveals that the onset and cessation of rainy seasons were vary in each SSPs. Themidland and highland part of the UBNB were characterized by a short length of rainy season (82130 days). Whereas, lowland part of basin was characterized by a longer length of rainy seaso140-150 days). Furthermore, extreme temperature indices showed a significant decrease in thenumber of cold days and nights, and an increase warm days and nights. Conversely, rainfallindices showed a decreasing trend. Therefore, it is critical to boost capacity and decreassusceptibility to extreme temperatures. Thus, this study will enable the development of effectivadaptation and mitigation measures for climate extreme hazards to combat the effects of excessivheat in the UBNB. In addition, the community in the study area should introduce quick-matureand drought-resistant crops.