A girl wearing China's national flag, jumps in front of the National Stadium, or "Bird's Nest," agains blue sky. [Xinhua]

The Beijing Meteorological Bureau (www.bjmb.gov.cn) forecast a high of 32 degrees Celsius (86 degrees Fahrenheit) and air quality at grade 1 -- the best possible rating.

The air has been largely clear, thanks in part to occasional heavy rain.

Saturday is the last big day of medals, with 32 on offer, including the last diving gold, in the 10m platform, which China's Zhou Luxin is favoured to win to give the hosts a clean sweep of all eight diving medals.

Apart from Sunday's men's marathon, the athletics end on Saturday. The highlight will be Ethiopian Kenenisa Bekele's attempt to add the men's 5,000m to his 10,000m title, a double already achieved by female compatriot Tirunesh Dibaba.