In Guangdong, five people were killed, 15 missing and 13 trapped as of Monday, local emergency management authorities said.
Sishui, a town in the province, logged 369.3 millimetres of precipitation in 24 hours. The deluge prompted officials to raise emergency response levels, and dispatch helicopters to evacuate and deliver supplies to those affected.
Four people died and two went missing in neighbouring Fujian due to rainstorms that the provincial meteorological bureau classified as an "extreme event", state broadcaster CCTV reported.
Downpours in Fujian's Wuping county since Sunday afternoon had caused 378 homes to collapse and prompted authorities to launch an emergency flood response.
Over the past few days, heavy rains have inundated the province, breaking a historical record in Wuping county. Economic losses in the county totalled 415 million yuan ($A87 million), state media reported.
Many parts of southern China have been impacted by rains over the past few days, prompting several localities to issue flood warnings and advisories.
In Jiangxi province, the average rainfall was 24 mm between from 8am Sunday and 8am Monday, with 288 weather stations in 56 counties recording considerable precipitation, state media said.
In Chongqing, torrential rains caused water levels of five rivers to rise by one to three metres, according to CCTV.
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