The announcement came on Sunday when temperature rose to 36.2 degrees Celsius in the capital.
The highest temperature was recorded at 38 degrees Celsius in Jessore, the hottest in seven days.
The fourth heat wave of the season from March and May hit Dhaka and Khulna divisions, Pabna, Tangail, Faridpur, Chandpur, Noakhali, Barisal and Patuakhali, said Abdul Kalam Mollik, a spokesman for the Met office.
Storms may hit parts of the country this month, he said.
Some areas of Mymensingh and Sylhet divisions may get hit by hailstorms or thunderstorms along with gusty winds.
Other areas will remain dry with cloudy skies, according to a weather forecast.
Mild heat wave occurs when the mercury rises to 36-38 degrees Celsius while a medium heat wave is marked with temperature around 40 degrees Celsius.
In meteorological terms, a severe heat wave occurs when temperature goes beyond 40 degrees Celsius.
Courtesy of bdnews24.com