Travel chaos came amid torrential rains in Hong Kong and the worst flooding to hit Shenzhen in six years, crippling an intercity railway to Guangzhou and grounding flights.
The disruptions continued today as the first Hong Kong-bound train, Number T801, schedued to depart Guangzhou at 8.19am was cancelled due to the weather, the MTR Corporation said. But other trains on the line would not be affected.
Watch: Shenzhen hit by worst flooding in six years
At Chek Lap Kok airport, a total of 23 flights were cancelled and 336 were delayed yesterday and early this morning due to storms. The red storm warning signal, indicating rainfall exceeding 50mm an hour, remained in force today.
Among the worst-hit were Hong Kong Island, Tai O on Lantau Island, Lamma, Cheung Chau and the northeast New Territories, which saw 300-400mm of rainfall in 24 hours ending at 8am today, according to the Hong Kong Observatory.
There were 3,436 lightning strikes from 7pm to 8am today across the territory.
Commuters were advised to be on the alert today as thunderstorms are expected to continue and many roads are flooded from four days of rain.
More than 100 passengers were believed to have been stranded at Hung Hom MTR station last night after at least 12 scheduled inter-city trains between Hong Kong and Guangzhou were cancelled.
Floods were blamed as more than 430mm of rain fell on the Longhua district of northern Shenzhen by 7pm, according to the Shenzhen Meteorological Bureau.
"We were alerted by the mainland authorities that services had to be cancelled because of bad weather and flooding. It is not certain when the services will resume," an MTR Corp spokesman said, adding that affected passengers could contact the company for a refund within 30 days.
One of the stranded passengers at Hung Hom, a visitor from Guangzhou, said: "It is very frustrating. We don't want refunds. We want to go home."
The high-speed railway service that links Guangzhou and Shenzhen was also suspended and at least 197 flights at Shenzhen's airport were cancelled by 10pm in response to the deluge. Shenzhen Meteorological Bureau said it was the heaviest rain since 2008.
The authorities in Shenzhen repeatedly urged residents to stay home throughout the day as roads and streets across the city were inundated. The local government received more than 150 reports of flooding.
In Hong Kong, the border areas and northern New Territories were the hardest hit by the heavy rain, with the Observatory issuing the red rainstorm warning from 9.50pm to 11.55pm.
Knee-deep floods were reported in Shek Wu Wai village near Ma Po, Yuen Long, while vegetable farms were covered in water in Yin Kong, Sheung Shui.
According to the Observatory, one or two thunderstorms are expected this morning, and the wet weather will ease off later in the day. It forecast that the weather would improve gradually tomorrow.
While there were no reports of deaths in Hong Kong or Shenzhen, extreme weather in other parts of southern and eastern China killed at least 21 people.
In Qingdao city, Shandong province, 18 workers at a recycling plant living in temporary accommodation were killed and three more were injured after heavy rain caused a retaining wall to collapse, crushing the housing structure.
In Hunan and Guangxi provinces, heavy rainstorms killed at least three people and forced the relocation of more than 54,000 residents, Xinhua reported.
Meanwhile, there was 10cm of snow in Shandan county in Gansu on Saturday, the first since the beginning of summer on China's agricultural calendar.
The area often experiences snow in the spring due to cold air from Xinjiang meeting warm air from the south.
The National Meteorology Centre forecasts that the rain will persist in Zhejaing, Fujian and Guangdong today before the weather improves later in the week.