BEIJING -- The national weather observatory continued its blue alert for sandstorms on Thursday, forecasting windy and dusty weather in North China in the next three days.

From Thursday to Saturday, parts of Xinjiang, Inner Mongolia, Ningxia, Gansu, Shaanxi, and the western part of northeast China will be affected by the dust, said the National Meteorological Center (NMC).

Meanwhile, a strong cold front will sweep North China including areas of Inner Mongolia and northeast regions, bringing a temperature drop of up to 12 degrees Celsius, said the NMC.

Since Wednesday, the country's northern areas have witnessed the most severe sandstorms this year, affecting more than 10 provincial-level regions and covering an area of 1.63 million square kilometers, NMC data showed.

The sandstorms have resulted in serious air pollution. Most monitoring stations in Beijing showed PM10 and PM2.5 readings of more than 1,000 micrograms per cubic meter and over 400 micrograms per cubic meter, respectively, as of noon Thursday.

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