National observatory issued Sunday an orange alert for rainstorms expected to hit the country's eastern and southwestern regions over the coming 24 hours.

Some parts in Heilongjiang, Jilin, Liaoning, Inner Mongolia, Hebei, Tianjin, Shandong, Sichuan, Yunnan, Guangdong and Hainan will see heavy rains, with downpours and thunderstorms in some places, the National Meteorological Center said.

On Saturday, the heaviest rain in 61 years lashed Beijing, leaving 10 people dead and 14,500 city residents evacuated, municipal authorities said.

According to statistics at 20 weather observing stations in Beijing, the city received 170 mm of precipitation on average as of 6 a.m., the largest since weather records from 1951. A township in Fangshan District was hit by the largest rainfall of 460 mm.

The center issued Saturday evening its first orange rainstorm alert since 2005, predicting the rain to last over 20 hours till Sunday morning.

Chinese meteorological authorities use a four-tier color-coded weather warning system from "blue," "yellow" to "orange" and "red."

Meanwhile, a persistent heat wave will continue to scorch regions south of the Yangtze River, with temperatures reaching up to 37 degrees Celsius, the center said.