The chance of rain during the opening ceremony is slimmer than reported earlier, but thunderstorms, high temperatures and muggy skies still pose a threat to the Beijing Olympics.

An analysis of weather data from 1975 to 2007 from the Haidian district observatory, the closest to the "Bird's Nest" where the opening ceremony will be held, shows the chance of rain spoiling the show is 41 percent, said Qiao Lin, chief forecaster of China Meteorological Administration (CMA) Tuesday.

An earlier analysis, based on the data from the entire city, suggested there was a 47-50 chance of rain on Aug 8.

Qiao held out further hope for a perfect opening day for the Games, saying that even if it rains, it will be light.

But inclement weather could still play spoilsport during the 17-day Games, said Chen Zhenlin, deputy director of CMA's forecasting service and disaster mitigation department.

"Thunderstorms, heavy rain, high temperatures, muggy skies and even hailstorms could be a problem," said Chen, who is also director of the Olympic Weather Service Center.

Beijing has made every possible effort to prevent bad weather from interrupting the Games. It even rescheduled it from July 25-Aug 10 to Aug 8-24 to avoid the rainy season.

But global warming has made extreme weather a more frequent and intensive affair, CMA spokesman Yu Xinwen said. This year has been especially bad for China, starting from the snowstorms in February to the recent heavy rain and floods and Beijing experiencing its wettest June in 15 years, Yu said.

Meteorological offices will intensify their efforts, especially during the Games, to forecast accurate weather on an hourly basis. And all forecasts will be both in Chinese and English.

Weather experts from former Olympic host countries, such as the US, Canada, Japan and Australia, will be in China in August to share their expertise and technology, Chen said.

Weather forecasting satellite Fengyun-3A (FY-3A), launched recently, is expected to begin functioning before the Games, and, together with FY-1D, FY-2C and FY-2D satellites, offer more precise weather data, Yu said.

Modifying the weather artificially during the Games is a possibility, he said. Planes and rockets could spread silver iodine and dry ice high into the atmosphere to target cumulonimbus clouds and induce rain before the clouds veer toward the Olympic venues.

But the technology can only prevent light rainfall, he said. It is powerless against thick, widely spread, huge mass of clouds.