On that day, the weather information was updated every six minutes by Guo's bureau. While people were enjoying the fireworks show in the evening, meteorologists were firing rockets to disperse threatening rainy clouds coming from the southwest. In order to keep the "Bird's Nest" dry, a total of 1,104 rockets were launched.

Guo's team provides weather reports during the Games. The team of 36, selected from more than 200 outstanding forecasters and technicians nationwide, must monitor the weather conditions closely, and hold several consultations everyday. As the team's spokesman, Guo fields interviews and press queries.

Graduating from the prestigious Beijing University in 1984, Guo has been working at the BMB for over 20 years. He said, "I've witnessed the great progress Beijing has made in modernizing weather service, especially since 2001 when the city won the bid for the 29th Olympic Games."

Guo well remembered the capital's primitive weather service four years ago. On July 10, 2004, Beijing suffered a freak heavy rainstorm, which paralyzed traffic and submerged cars. By 10 a.m. the next day, a total of 61 streets had suffered traffic jams, eight road sections under viaducts were blocked by the rainwater, and more than 200 flights were delayed.

"At that time, the weather monitoring depots observed and reported once an hour, and the data wouldn't reach the observatory until 20 minutes later. It was 1 hour and 20 minutes later when we knew that situation under Lianhua viaduct on that day," he said, referring to the worst affected section of road.

"Nowadays, the weather depots observe every five minutes, and the transmission of data only takes 10 minutes, which means it only takes the forecaster 15 minutes to know the weather conditions."

The rainstorm in 2004 rang alarms for Chinese meteorologists. After that, new observing technologies were introduced and dissemination of early warning signals enhanced.

Guo and his teammates were under great pressure as they knew how crucial the weather would be to the opening ceremony held in the roofless "Bird's Nest". Fortunately, with the help of four meteorological satellites and seven meteorological Doppler radars in Beijing, the BMB were able to release a detailed weather forecast two days in advance of the opening ceremony.

It then rained on Aug. 10-11, causing the delay of several matches including tennis. "More rain is expected on August 16 and 17," said Guo. "We will provide the latest weather forecasts each hour for weather-sensitive sports, so that the organizers can make better arrangements according to the weather condition."

Considering Beijing and other co-host cities are in rainy season now, "meteorology departments have also improved the Olympic weather service for the public," said Guo. "Information on weather forecasting and warning are offered on television, radio, the Internet, bus LCD, cellphone short messages and other media."

The public can also get weather information through hotline 12121, or on the website of Beijing Olympic weather service (www.bjweather.cn).

"Both Chinese and English information are provided, for international visitors, journalists and athletes' convenience," Guo said.

As for his team, Guo said, "We will work until the Paralympic Games finish on September 17."

"We aim to do a good job in weather service. A good medal for that, that's our goal," he added.