Heaviest rains in 60 years kill 37 in Beijing

(Recasts with new death toll, adds details)

BEIJING, July 22 (Reuters) - The Chinese capital's heaviest rainstorm in six decades killed at least 37 people, flooded streets and stranded 80,000 people at the main airport, state media and the government said on Sunday.

The storm, which started on Saturday afternoon and continued late into the night, flooded major roads and sent torrents of water tumbling down steps into underpasses.

The Beijing city government said on its official microblog at least 37 people had died, including 25 drowned, six crushed in collapsing homes, five electrocuted and one struck by lightning.

More than 500 flights were cancelled at Beijing's Capital International Airport, the Beijing News added.

The subway system was largely unaffected by the floods but was swamped with people desperate to get home and unable to use cars, buses or taxis.

The city received about 170 mm (6.7 inches) of rain on average, but one township in Fangshan District to Beijing's west was hit by 460 mm (18.1 inches), Xinhua news agency said.

The Beijing city government said on its website (www.beijing.gov.cn) it was working to get the metropolis back on its feet, and warned people to prepare for further bad weather.

"The weather forecasters say that from late July to early September this city is prone to flooding, and there could be further large-scale storms or extreme weather," it said.

Many residents took to China's popular microblogging site Sina Weibo to post dramatic pictures of the storm. Some complained the city should have been prepared, especially as the government had issued a severe storm warning the day before.

"It was forecast early on that Beijing would get torrential rain, so why were pumps and other facilities not prepared in time?" complained one user.

The clouds had at least one silver lining.

The official pollution index, which had showed an unhealthy rating before the storm hit, registered "excellent" on Sunday, with the air noticeably free of its normal acrid smell. (Reporting by Ben Blanchard; editing by Andrew Roche)