The intense downpours 激烈的暴雨 and strong winds that hit northern China starting on Sunday will continue for an extended period 延长时期 in a wide range of areas 广大区域 , greatly increasing the risk of natural disasters 自然灾害, the National Meteorological 气象 Center said on Monday.

The rainfall in the region on Sunday and Monday was the heaviest since the flood season began in June and marks the start of northern China's monthlong 一个月长 rainy season.

Though heavy rain is common 常见 around this time of year, which marks the start of northern China's rainy season, "it has come a little earlier than in normal years," said Zhang Fanghua, the center's chief forecaster 气象预报员. The average duration 持续时间 of northern China's rainy season is from July 18 to Aug 18, she added.

The heavy rainfall in Beijing and Tianjin and in Hebei, Shanxi and Shandong provinces is similar to the extreme rains between July 18 and 20, 2016, that caused urban 城市 flooding, mountain torrents 急流 , mudslides 泥石流, landslides 塌方 and other disasters, she added.

The center forecast 中央气象 that starting on Tuesday, the heavy rain will move eastward as well as northward, so rainfall in Beijing and Hebei province will be significantly 显著 weakened.

Between July 14 and 20, lighter rainfall is expected to linger in northern China and the Yangtze and Huaihe river regions, while Southwest China's Sichuan province will experience heavier rain than other places, the center said.

By Monday morning, heavy rain had closed several sections of highway in Hebei and Shanxi provinces, and many flights were canceled in Beijing, local authorities said. Hail also hit parts of Hebei province and Beijing.

Meteorological 气象的 stations in Hebei's Jize county and Henan province's Huaxian county set records 设置记录 with precipitation 降水量 of more than 200 millimeters, the center said.

Zhang, the meteorological center's forecaster, said the low vortex 旋转 system, a type of cold low pressure, brought abundant 丰富 water vapor 蒸汽 and unstable 不稳定 energy to the northern areas.

"The system that usually moves slowly is a favorable 有利 condition for rain to last long and accumulate 积累 in certain 某些 areas," she said.

The National Meteorological Center had issued a yellow alert 预警 for heavy rain and another alert for thunderstorms on Monday. A yellow alert is the third-highest of a four-tier system, with red being the most severe 严重 , followed by orange, yellow and blue.

The center said that when a yellow alert is issued, traffic management departments should take control measures based on road conditions and give traffic guidance 引导 . Other relevant 有关 departments 部门 should promptly 及时的 clear drainage 排水 outlets 网.

It suggested that people avoid riding bikes or driving in the rain, and should shut off outdoor power sources in low-lying areas, refrain 节约 from outdoor activities in open areas and take care around dilapidated 破败的 or damaged 损坏的 houses.

Meanwhile, for the next week in southern China, the Yangtze and Huaihe river regions are bracing 迎接 支架 for the summer's hottest, most sultry 闷热 days, with little rain-a period that began on Sunday and could last for 40 days and bring temperatures above 35 C, the center said.