Torrential rain battered Southern China on Sunday, causing flooding and forcing tens of thousands of evacuations in the country’s most populous province, as a waterspout appeared briefly in Hong Kong and forecasters warned of potentially severe flooding.

Rain has been falling in Guangdong, which has a population of about 127 million, since last week. It intensified over the weekend, hammering the north of the province and the Pearl River Delta in the south, which includes Guangdong’s capital, Guangzhou, as well as the cities of Hong Kong and Macau.

The city of Yingde, in Guangdong’s north, received nearly a foot of rain from Friday to Sunday, the state-owned newspaper China Daily reported on Sunday. Nearly 20,000 people were evacuated and nine rivers were at risk of overflowing, it said.

In Guangzhou, the Longxue neighborhood received nearly five inches of rain over four hours on Sunday morning, the highest amount in the province.

The Beijiang River, a tributary of the Pearl River, flooded on Saturday night, China’s Ministry of Water Resources said on Sunday. As the downpour continued, the river faced a risk of an “exceptionally large” flood through Monday, the ministry said.

And in Hong Kong, a Chinese territory south of Guangdong, a waterspout was sighted over water by the local meteorological agency on Sunday morning. Waterspouts are whirling columns of air and water mist that form when cold air moves over warmer water, drawing up moisture.

There were no reports of the waterspout’s causing damage, and a rainstorm warning for the city was canceled at 2 p.m. But forecasters warned of violent winds and possible flooding.

Heavy rain was also affecting parts of the neighboring Chinese provinces of Guangxi, Jiangxi and Fujian on Sunday.

The heaviest rain was forecast to shift from the north to the east of Guangdong on Monday, and some areas could receive up to 10 inches of rain over 24 hours, according to the China Weather Network, an arm of the country’s meteorological authority. The rainfall was expected to begin easing on Tuesday.

Thunderstorms and sometimes heavy showers were also forecast for Hong Kong on Monday.