Cold air has brought the biggest snowfall of the winter to Beijing, Tianjin and neighboring areas, and meteorological authorities are warning that temperatures could further plunge by six to 14 degrees in parts of North and East China in the next two days. The snow, which began falling before midnight Saturday and stopped before dawn, had caused closures of more than 10 highways on Sunday morning. At the capital airport, 71 flights were delayed by de-icing or canceled as of 10 am. Meanwhile, the national meteorological center issued a cold alert on Sunday morning, warning of strong winds and plunging temperatures in the next two days. Shandong, Henan, Hebei and Shanxi provinces are among those expected to be affected most. The national forecaster said the cold is expected in many areas to clear the lingering fog that has shrouded much of North and East China in the past few days. On Saturday, heavy fog shrouded Beijing before it rained and snowed, forcing local metrological authorities to issue the first yellow alert of fog in three months. The low visibility forced the delay or cancellation of 158 flights at the capital airport and the city's PM2.5 index -particulate matter measuring 2.5 micrometers or less - also stood far above standard, showing poor air quality. The fog dispersed on Sunday morning and the sky cleared up after the snow. Li Jin, deputy head of the Beijing meteorological bureau, said that the snowfall Saturday morning was the largest Beijing had this winter. It was also the biggest snowfall in Tianjin, according to the city's meteorological bureau. "It is not rare for Beijing to get snow in late winter because there is more warm and moist air at this time of the year," Li said. However, to many Beijing residents, the late snow came as a pleasant surprise, and many went outside to enjoy it. Chen Zhiqiang, an official with the Beijing municipal administration center of parks, said the authority estimated that 280,000 people visited parks on Sunday, 20 percent more than is usual on weekends. On Sunday morning, Shanghai was still cloaked in heavy fog, but experts say it will clear after the cold front arrives on Sunday night. "Most parts of the Yangzte River Delta region will be rainy and the temperature will keep dropping, bottoming out at 4 C on Wednesday morning in Shanghai," said Fu Yi, the chief meteorologist of Shanghai Urban Environment Meteorology Center. The lingering fog caused severe road and air travel disruptions nationwide over the weekend. It was considered to be the cause of four separate accidents involving more than 60 vehicles on an expressway in Xuzhou, Jiangsu province, on Saturday morning. At least six people were been confirmed dead and 30 others were injured, six of them critically. Local authorities say more casualties were feared as rescuers continued searching for victims. Intense fog was also blamed for the closure of 130 toll stations and 15 highways in East China's Shandong province on Saturday, the most severe case of road closures caused by heavy fog in recent years. On Sunday, more than 2000 passengers were stranded at the Tianhe airport of Wuhan, Hubei province, as heavy fog shrouded the airport. All departures and arrivals were delayed until 10 am because of the low visibility.