The summer high temperature trend over the northeast side of the Tibetan Plateau was investigated by using the daily high temperature data (1960-2003) of 80 stations there and 30 years (1971-2000) NCEP/NCAR reanalysis data, and by selecting the typical case of abnormal high temperature, the circulation characteristic and the possible region influenced by the same weather process were analyzed. It was found that if the westerly index varied from high to low and maintained, the high temperature weather would occur and last, on the contrary, it would end. The main circulation characteristic of the high temperature weather was the addition of the South Asia high and the Northwest Pacific subtropical high. The positive temperature advection of the upper level and the negative vorticity throughout the whole level also induced the persistence of the high temperature weather. The temperature change over Lanzhou and its surrounding areas was consistent, when temperature high over Lanzhou, the northeast side of the Tibetan Plateau would reach the high temperature at the same time.
