Abstract:During the summer of 2017 (June to August), the average precipitation over China was 348.6 mm, which is 8.1% more than normal (332.6 mm). Two rainfall bands were observed over eastern China. The East Asian summer monsoon (EASM) was weaker than normal, while the west Pacific subtropical high (WPSH) was significantly stronger than normal with southward ridge position. The “-+-” circulation pattern was located in Eurasian mid-high latitude with positive anomaly over the Lake of Baikal region. The cold SST in the middle-east of equatorial Pacific in the early winter changed to warm phase in the summer of 2017, and the 4th rain pattern, e.g. above normal rainfall in southern China, prevailed, while the blocking high over the Lake of Baikal appeared frequently. The major precursory signals of southward rainband are the weakened cold sea surface temperature (SST) in the middle-east of equator Pacific in early winter 2016, the positive triple SST in the North Atlantic in spring 2017, and the decreased snow cover in Eurasia from autumn to winter in 2016. Their common effects benefit the blocking high formation over the Lake of Baikal.