Figures offered by the center show five rounds of heavy rainfall have hit southern China since last month, producing at least 200 millimeters of accumulated precipitation on about 1.5 million square kilometers of land.

Hu Xiao, chief forecaster with the China Meteorological Administration, said the abundant water vapor is to blame.

"The Pacific and Indian oceans are two powerful suppliers of water vapor in our country. In summer, wind usually blows from south to north, transporting the vapor from the ocean to the land," he said.