Abstract: ysis were conducted upon the extreme heat and drought event in the basin during the summer 2022 and upon the impacts of this event on hydropower resources. Preliminary analysis was also carried out in  the cause analysis regarding the anomalies of the sea temperature and the atmospheric circulation. The results showed that: (1) The summer 2022 reached the highest in the average temperature and high temperature days, and the lowest in the average precipitation for the same period since 1961 in the YRB. Heat wave and deficit rainfall led to the rapid development of meteorological drought, which covered the largest area in the basin for this summer since 1961. (2) Continuous high temperature and deficit rainfall significantly reduced stream flow for the mainstreams and tributaries in the basin, creating an unusual “Dryness during the Flood Season” phenomenon. The runoff in August 2022 was reduced by 45% to 65% compared with that in the same period in historic records. The inflow, outflow and hydropower generation of the major large hydropower stations in the YRB significantly decreased, reaching the lowest or almost the smallest during the last 5 years. (3) The weak transport of water vapor driven by the abnormal high and westward extension of the Western Pacific Subtropical High (WPSH) was regarded as the main factors causing this extreme heat and drought event. Moreover, the continuous development of La Nia was an important SST background. The SST in the central equatorial Pacific was relatively low, while the SST in the western Pacific warm pool was abnormally warm, and therefore, the Walker Circulation was enhanced. By modulating the Hadley Circulation, an anticyclone was developed over the northwestern Pacific and finally strengthened the WPSH