Published: 2022-06-21 16:49:31 BdST
Guangdong province's Shaoguan city, where average rainfall since late May has broken records, raised its flood alert to the highest, Level 1.
Authorities asked residents of communities along river banks and in low-lying neighbourhoods to move to higher ground, after floodwaters hit a 50-year high, state television reported.
The city's flood, drought and wind control headquarters said shutdowns may be enforced at construction sites, businesses, public transport and docks while workers unable to show up at work should not be forced to do so.
The water level of Guangdong's Beijiang River also rose past warning levels, surpassing a 1994 record.
Guangdong's Qingyuan city, near Shaoguan, also raised its flood alert to the highest level at around noon as the waters rose.
In Jiangxi province to the northeast, authorities raised a flood "red alert" after 485,000 people in nine districts were affected, Xinhua news agency said. It did not elaborate.
Economic losses reached 470 million yuan ($70.21 million), with 43,300 hectares of crops destroyed, Xinhua reported.
The summer rainy season brings floods to China almost every year but environmental groups say climate change can bring heavier and more frequent downpours.
There is also the risk that the impact of the disruption floods bring in China can be felt further afield as Chinese goods become more important in global supply chains.
This spell of heavy rain across southern provinces was expected to peak on Tuesday and it was then forecast to shift northward from Wednesday.
Regions north of the Yangtze River have been experiencing searing heat, pushing up power consumption the past weekend.
China's Central Meteorological Observatory maintained a high temperature "orange warning" for northern areas such as central and southern Hebei, most of Beijing and parts of Shandong, Tianjin and Henan.