GUANGZHOU, March 30 -- Heavy rains have grounded flights and stranded passengers at major airports of south China's Guangdong Province, airport authorities said Sunday.

According to the Baiyun International Airport in Guangzhou, nearly 103 flights were delayed and 101 departing flights and 72 inbound ones were canceled due to thunder and rain, which has stranded thousands of travellers as of 06:40 p.m.

Meanwhile, in Shenzhen Bao'an International Airport, thunderstorms have led to the delay of 49 departing flights and caused cancellation of about 11 outbound flights to Beijing, Hangzhou, Chongqing and Shanghai as of 05:00 p.m. on Sunday.

Affected by the weather, nearly 21 incoming flight were forced to land in Shenzhen from neighboring cities like Guangzhou and Zhuhai, the airport said.

Airport authorities in Guangzhou has issued a red rainstorm alert at 12:30 p.m. on Sunday, while that in Shenzhen has also issued a blue one.

China has a four-tier rainstorm alert system, with red being the most serious, followed by orange, yellow and blue.

The airports and airlines were ready to provide emergency services to passengers.