BEIJING, June 25 (Xinhua) -- China's national weather observatory issued a yellow alert for rainstorms Monday, as heavy rain will sweep most parts of the country.

From Monday afternoon to Tuesday afternoon, heavy rain or storms will hit parts of Shandong, Henan, Shanxi, Gansu, Sichuan, Guangdong and Heilongjiang, with some of these areas expecting thunderstorms, according to the National Meteorological Center.

Rainfall could exceed 150 mm per hour in some regions, the center said.

It warned local authorities to reduce outdoor activities and take precautions against flooding, flash floods and landslides.

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