A severe heatwave is scorching the districts of Chuadanga and Bagerhat while a mild to moderate heat wave is sweeping over Rajshahi, Mymensingh, Dhaka, and parts of Khulna, Barisal, Chittagong and Sylhet divisions.
The severity may ease in some other places, said a Met Office bulletin.
Chuadanga recorded the highest temperature of this season at 40.6°C on Tuesday.
Meteorologists say that almost every year in April, there are often two or three moderate heat waves and one or two strong heat waves in Bangladesh. However, according to weather experts, this year's heat wave period is expected to exceed previous years.
With the looming threat of heat waves becoming more frequent and intense, it is crucial now more than ever to equip ourselves with the knowledge and strategies to stay safe and healthy during extreme heat conditions.
According to the World Health Organization (WHO), when a heatwave persists, people should aim to keep their living space cool.
The room temperature should be checked between 8am and 10am, at 1pm and after 10pm. Ideally, the room temperature should be kept below 32°C during the day and 24°C during the night.
This is especially important for infants or adults over the age of 60 or who have chronic health conditions, the WHO says.
All the windows and shutters in the home should be opened at night and early morning when the outside temperature is lower. During the day, the windows and shutters, especially those facing the sun, should be kept closed.
Artificial lighting and electrical devices have to be turned off, if possible.
Hanging shades, draperies, awnings or louvres on windows that receive morning or afternoon sun, and wet towels cool down the room air and the humidity of the air increases at the same time.
If the residence is air-conditioned, the doors and windows should be kept closed to keep the room cool. Electric fans may provide relief, but when the temperature is above 35°C, it may not prevent heat-related illness.
As mild to moderate heat waves sweep over various divisions and districts of Bangladesh, staying hydrated and cool becomes essential to beat the heat and stay healthy.