BEIJING--On the first day of autumn under the lunar calendar, Beijing was wrapped in a persistent haze with cloudy skies on Thursday. The humidity made it feel stiflingly hot, even though it was actually cooler -- with a high of 31 degrees Celsius (about 88 Fahrenheit) -- than some days previously.

But weather experts told Xinhua that cooler weather was expected during the Games, which start on Friday, and athletes would probably see no "sauna weather" ahead.

"Heat and humidity will recede after the lunar-calendar autumn begins," Guo Wenli, director of the climate office with the Beijing Meteorological Bureau (BMB), said.

Ancient Chinese followed the lunar calendar to indicate climate changes during the year, and the calendar remains an important reference today in China.

"High humidity and high temperatures are not expected to combine to create a 'sauna' in Beijing in August," said Wang Yubin, BMB's deputy chief engineer and deputy head of the Olympic weather service group.

The maximum humidity usually emerges in the early morning or at the latest by noon in August, while the highest temperatures are usually recorded in the afternoon, according to the BMB's analysis of weather records, Wang explained.

The ancient Chinese said that the weather remains hot 10 days after the official start of autumn to remind people of summer.

But city weather records show that extremely high temperatures (above 35 degrees Celsius or 95 Fahrenheit) were recorded only twice in history after the lunar-calendar autumn began.

Autumn is the best season for the Chinese capital, usually featuring clear blue skies, cool air, and golden leaves in the mild sunshine.

The city will get cooler, especially after each rainfall, as autumn closes in, and the weather will be even better during the Paralympics, which end in September.

The Environmental Protection Bureau said pollution in the city was read at 96 on Thursday,

within the "fairly good" range of between 51 to 100, but very close to the "slightly polluted" range. However, environmental experts are confident of air quality during the Games, as August has historically been the month in which the most days meet quality standards.

Friday, the day of the opening ceremony, is expected to be cloudy with scattered rain and a high of 30 degrees Celsius (86 Fahrenheit).

"The weather will mainly be overcast during the opening ceremony on Friday," said China Meteorological Administration spokesman Yu Xinwen on Wednesday.

Organizers said the ceremony would be unaffected by drizzle and small adjustments would be needed in case of moderate rain, but they feared torrential rain the most.

Experts said such downpours are unlikely after the start of the lunar  autumn in Beijing.