BEIJING, Sept. 13 -- The National Meteorological Center (NMC) on Saturday maintained a blue alert for heavy rain in the country's western regions, which have seen substantial precipitation in the past week.

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

From Saturday to Sunday morning, parts of the Sichuan Basin and Chongqing Municipality in southwest China and northwest China's Shaanxi Province will see heavy rains or rain storms, with some areas to receive precipitation of 100 to 150 mm, the NMC said in a statement.

Areas of Hubei Province, Guangdong Province, Guangxi Zhuang Autonomous Region and Inner Mongolia Autonomous Region will also be hit by strong rains, it added.

Typhoon Kalmaegi, which is moving westward from the Philippines, strengthened to a severe tropical storm on Saturday morning. The observatory forecast that the storm will affect Chinese waters and the country's southern coast starting Sunday afternoon.