Eastern and northern China saw temperature drops that brought frost and heavy snowstorms since Monday, closing highways and damaging crops across the region, China Meteorological News reported on April 15.

Yang Guiming, chief forecaster at the National Meteorological Center, said the frost in east China and the snowstorms in the northern provinces are a result of two cold air currents caused by the same weather system.

A mid-level cold air front that formed in Siberia caused temperatures to begin declining April 8. Before they could rise again, a colder air current from the Mongolian Plateau swept across China, especially in the north.

Yang said that although cold snaps have rarely happened in the last decade, they have occurred several times in the past 30 years, so it is a normal phenomenon in the spring.

He said the cold air will be over by Thursday and the temperature will rise gradually until April 18, when another cold air front comes in.