A heat wave will expand from northern China to the country's central and eastern regions in the coming three days, the meteorological agency reported Tuesday.

On Monday, much of northern China was in the grip of heat wave with temperatures in parts of Hebei, Shanxi, Shaanxi and Xinjiang hitting 40-42 degrees Celsius, according to the National Meteorological Center.

Maximum temperatures in 31 counties and cities in Xinjiang, Ningxia, Gansu, Shaanxi and Sichuan broke their record highs.

In the next three days, the agency forecasts the heat wave will expand southward. Central and eastern China will see temperatures rise to their highest this year.

The heave wave is estimated to sweep 21 provinces covering an area of 3.64 million square meters on Thursday.

The agency warned the public to take precautions against the heat. Flood-stricken areas in southern China should enhance hygiene and disease control efforts.