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１９９８年汛期长江流域发生了继１９５４年以来又一次全流域性大洪水，这场洪水是由于６～８月，长江全流域出现少见的持续性强降雨过程所造成的。主汛期降雨特点是：降雨过程频繁、暴雨连续不断；阶段性主雨带位置稳定，震荡幅度小，维持时间长；主雨带南北“拉锯”、上下游暴雨交替出现；暴雨集中，持续发生，滞留性强。暴雨的成因与主汛期和前期的雨情、环流背景、海温和各种有关物理条件等有关。从大气环流、海洋温度场异常点及降水、暴雨过程等方面进行分析研究表明：１９９８年６～８月大洪水与强厄尔尼诺事件有关，高空环流异常稳定，西北太平洋高压偏强，影响长江流域的冷空气活动频繁，暖湿气流活跃，台风活动异常偏少，与１９５４年相应天气活动特征存在一定差异。
In the flood season of 1998, another major flood occurred in the whole Yangtze River basin since 1954, which was caused by the rare and persistent heavy rainfall in the whole Yangtze River from June to August. The characteristics of rainfall in the main flood season are as follows: frequent rainfall rains, continuous heavy rainstorms; stable and fluctuating amplitude of the main rainstorm at the stage and long sustaining time; heavy rainfall at the north- Strong retention. The causes of torrential rain are related to the main flood season and previous rain conditions, circulation background, SST and various related physical conditions. From the aspects of the atmospheric circulation, the temperature anomalies in the ocean and the process of precipitation and torrential rains, it is found that the major floods from June to August 1998 are related to the strong El Niño event, the altitude circulation is abnormally stable, the high pressure in the western North Pacific is stronger, affecting the Yangtze River Basin Cold air activities are frequent, the warm and humid air currents are active, the typhoon activities are abnormally few, and there are some differences with the corresponding weather activities in 1954.