The worst storm to hit the city in more than 60 years dumped an average of 8.5 inches of rain in 16 hours with one suburb recording 18 inches in the same period, the journal Nature reported Tuesday.
"The storm was a result of a large weather pattern over northern China," Qiao Lin, director of the Beijing meteorology station, told the People's Daily. "But Beijing was the worst hit and had the most rainfall."
Qiao said he thinks this may be because the city is near a mountain range, where storms tend to form, and is an 'urban heat island' generating much more heat than the surrounding rural regions.
Chinese researchers say computer simulations suggest how different types of land surfaces and urbanization can affect an approaching storm.
The "heat island" effect can make atmospheric circulation become more vigorous and extra energy is available for a storm to develop above the city, they said.
"This is the first time that Chinese authorities have acknowledged the effects of intense urbanization on extreme weather events," said Fei Chen, an atmospheric scientist at the U.S. National Center for Atmospheric Research in Boulder, Colo.