The country is likely to witness a severe heatwave from today or tomorrow, according to a meteorologist at the Bangladesh Meteorological Department.

Currently, a mild to moderate heatwave is sweeping over all divisions of the country except Rangpur, according to a BMD bulletin this morning.

"A severe heatwave is likely to start today or tomorrow across the country and it will continue till April 16," Md Bazlur Rashid, meteorologist of BMD, told The Daily Star.

He said the ongoing heatwave is likely to continue till April 18, and the weather may return to normal after that.

The meteorologist also said that as the humidity is low, the heat feels intolerable this year, but humidity will also increase from April 16.

A heatwave occurs when the daily maximum temperature tops 36ºC over a large area and it is classified into three categories based on temperature -- mild, moderate, and severe.

According to BMD, a mild heatwave is when the temperature is between 36 to 37.9ºC, moderate between 38ºC and 39.9ºC, and severe heatwave happens when the temperature is 40ºC and above.