At least 10 people have died and 18 are missing after torrential rains battered Hebei province in northern China.
Officials evacuated more than half its 11.5 million people by noon (04:00 GMT) on Saturday from areas thought to be at high risk of landslides and floods.
Storm Doksuri, which hit mainland China last week, has brought the worst rains in 140 years.
China’s weather agency issued a red alert to warn people about the “geological risks”.
Hebei province, neighbouring Beijing is said to be one of the worst affected areas.
Clean-up operations are under way after the floods engulfed residential homes, destroyed infrastructure and submerged entire districts.
Aerial video footage of Hebei province shot by AFP showed entire shopping streets transformed into rivers of brown water, with farmland in the surrounding areas completely submerged.
Rescuers were seen using boats to transport instant noodles, bread and drinking water to residents who could not access basic supplies and feared leaving their homes.
In July alone, China’s Ministry of Emergency Management said that it recorded 142 people dead or missing because of the extreme weather.
Globally, millions of people have been hit by extreme weather and heatwaves in recent weeks.
Ma Jun, director of the Beijing-based Institute of Public and Environmental Affairs, an NGO, said: “China has suffered unprecedented extreme heatwaves since last year.
“These heatwaves are linked to global warming, and this is what most climate scientists around the world tend to agree.”
Doksuri made landfall in China’s south-east Fujian province on Friday, triggering landslides and floods before moving north towards the capital. Hundreds of thousands of Fujian residents were evacuated.
Doksuri, which came a week after typhoon Talim, also led to mass closures of schools and workplaces across the province.
