Severe thunderstorms and heavy hail struck Dongguan on Wednesday - and are believed to have killed nine people and seriously injured two others.
There were also 134 cases reported of people with less serious injuries, state media reported, citing the Dongguan Municipal Health Bureau.
The bureau said these figures would be investigated further. Dongguan is an industrial city located in China's Pearl River Delta.
Many neighbourhoods in Dongguan were hit by thunderstorms packed with heavy rainfall, strong winds and hail, causing substantial damage to homes and vehicles. The storm caused the collapse of temporary buildings and regional power blackouts.
Maximum wind speeds were recorded at 49.1 metres a second, and the greatest precipitation of rain was recorded at 40.6mm in Dalingshan.
Witnesses likened the egg-sized hail to “stones falling from the sky” and said they “sounded like endless drumming.”
The Dongguan Municipal Meteorological Observatory issued an orange hail signal on Wednesday afternoon. Observatory chairman said that it was the first hail signal issued since the system was established in 2006.
Thunderstorms and hail also affected other southern regions in China, including cities in Guangdong, Hunan, Jiangxi, Guizhou, Fujian, and Guangxi.
The observatory said the severe weather was a result of the annual "summer and winter monsoon transition". This often led to devastating thunderstorms, strong winds and some hail in China’s southern regions.
The observatory said the storms usually occurred between April and August. “It is rare to see hail in March,” the observatory chairman said.
The observatory forecasts that the unstable weather will continue fior the next few days. It advised people to avoid going out and to close their windows during future hail storms.
On Thursday, several other provinces were also experiencing bouts of extreme weather. Jiangxi, Fujian and parts of Guangdong and Guangxi were hit with 20 to 49mm of rainfall.
Thunderstorms struck Hunan and Guizhou. Severe rain and wind in Hunan's Yongzhou city was said to have caused the deaths of at least three people, according to Xinhua. Scores of buildings were damaged and 30 people were injured.