i thought i heard the commentator said South China at this time of the year has quite a bit of rain..
Anything around or south of the Yangtze river or Changjang, the longest river in China which roughly splits it up between the north and the south. The Yangtze River Delta region where it enters the sea is notionally referred to as Jiangnan (South of the River), roughly overlaps Jiangsu province (the "su" refers to Suzhou), Shanghai city, Zhejiang province and even parts of Anhui province.