BEIJING -- Beijing activated a city-wide Level-III emergency response for flood control at noon Tuesday, as authorities warned of heavy rainfall expected from Tuesday night through Wednesday.

The Beijing meteorological observatory said some areas could receive over 70 mm of rain within six hours or more than 100 mm within 24 hours.

An orange alert -- the third-highest alert level -- for heavy rain is in effect for seven districts, while red alerts have been issued for the suburban districts of Mentougou and Fangshan, where downpours may trigger flash floods.

The city's water and meteorological authorities jointly issued yellow warnings for waterlogging and mountain torrents, noting that urban areas are at risk of waterlogging from 11 pm Tuesday, while Fangshan, Mentougou, Changping and Yanqing districts are facing a higher risk of mountain torrents.

Flood control authorities have urged the public to limit travel, stay away from rivers and mountainous areas, and avoid parking in low-lying zones or under bridges.

China has a four-tier color-coded weather warning system, with red representing the most severe warning, followed by orange, yellow and blue.