Beijing’s terrain, surrounded by mountains to the west and north, is considered a natural rain trap, often intensifying downpours and complicating drainage. In 2012, the city recorded its worst floods in recent memory, with 79 fatalities, mostly in Fangshan district.

Beijing issued its highest alert for rainstorms on Monday, days after deadly deluges swept parts of the Chinese capital and triggered a rare apology from under-prepared officials.