BEIJING-- The capital will get cooler weather in August and Olympic participants are unlikely to suffer from the humid, hazy conditions that have affected the Games host city in recent days, local meteorological authorities said on Monday.

The Olympic Games will open on August 8, one day after the first day of autumn on the Chinese lunar calendar, which is expected to be less humid, said Guo Hu, director of the Beijing Meteorological Observatory.

Guo said that based on 30 years of data, the average temperature for the Games will be 24.9 degrees Celsius.

"The temperature and humidity will gradually drop and we will have better air quality and more comfortable weather in August," he said.

Beijing sweltered under damp, hazy skies over the past week. However, showers began on Monday and more rain is expected this week. The rain brought cool breezes and fresh air to the city on Tuesday as it marked the 10-day countdown for the Olympics.

July is always the hottest, rainiest month in Beijing. However, a rare humid period without rain from July 21-27 further pushed up temperatures and worsened visibility, according to Guo.

He said that the average temperature in July for the past 30 years was about 26.2 degrees Celsius. But the average temperature last week was 27.4 degrees Celsius.

Air quality will not affect the health of athletes during the Games, Du Shaozhong, vice director of Beijing Municipal Environmental Protection Bureau, reaffirmed on Monday, expressing confidence in the city's pollution control endeavor.

"The latest car control program has greatly cut major pollutants and inhalable particles in the air, but environmental protection authorities are working on emergency plans in case there are unfavorable weather conditions during the Olympics," he said.

Tough vehicle measures could be imposed if necessary, he added.

The international environmental group Greenpeace acknowledged in a report that Beijing has made significant progress in improving its environment as it prepares for the 2008 Olympic Games, but more permanent measures were needed to ensure long-term improvement.

The organization warned that temporary measures such as restricting car use or closing factories would not help in the long run. Beijing should take more ambitious measures to control air pollution, it said.

The China Meteorological Bureau launched a website on Monday offering comprehensive weather information and services for 2,913 domestic and foreign cities as well as for the Olympics.

Conditions will be updated every three hours. Forecasts and analysis for Beijing and six other Olympic co-host cities are also available.