The heaviest rainstorm this summer pounded the capital city on Thursday afternoon, causing flight delays and cancellations not only in Beijing but nationwide.

The Beijing Meteorological Bureau issued a blue rainstorm warning on Thursday, which means 50 millimeters of rain will fall within 12 hours in the city.

By 5 pm, the city had received 35 millimeters of precipitation, according to the bureau.

"Precipitation in the Shijingshan district reached 165 millimeters by 5:30 pm," said Sun Jisong, chief engineer of the bureau.

The rain is expected to cool the city for at least two more days, wiping away the heat and humidity that have smothered the capital in the past few days.

An airport spokesman said the torrential downpour caused 144 flights to be canceled and 93 flights delayed for more than an hour at the Beijing Capital International Airport by 9 pm Thursday.

In a ripple effect, the serious delay at the capital airport, a hub connecting cities nationwide with hundreds of flights a day, has caused many other airports to suffer paralysis.

Yan Jichun, a 31-year-old doctor who planned to fly to Beijing on Thursday afternoon for a conference on Friday, said his flight to Beijing from Ganzhou in East China's Jiangxi province was canceled due to the downpour in Beijing, and some 100 passengers, Yan included, were sent to local hotels.

"It's obvious I can't make it tomorrow," said Yan. "It's such bad luck. It's my first time going to the capital, yet I'm delayed here due to the rain in Beijing."

By 5 pm, 87 departing flights were delayed and four canceled at Chengdu Shuangliu airport in Southwest China's Sichuan province, and 114 flights were delayed and five canceled at Shanghai Hongqiao airport, according to civil aviation information website www.wcarn.com.

In addition, the landing of tropical storm Haima has caused flight delays in South China.

Haima, the fourth storm to hit China this year, made landfall over the coast of Guangdong province at 10:10 am on Thursday, packing strong winds and unleashing torrential rains, meteorological authorities said.

As a result, 161 departing flights were delayed and six canceled at Guangzhou Baiyun airport in the Guangdong provincial capital by 5 pm, according to www.wcarn.com.

At Shenzhen Bao'an airport in the same province, 105 departing flights were delayed and three canceled.

Airports suggested passengers follow updates of flight schedules and rearrange their plans accordingly to avoid unnecessary transportation delays or cancellations due to the weather.