One to three low pressure systems are likely to form over the Bay of Bengal this month and one to two of them may intensify into depression or cyclone, Bangladesh Meteorological Department (BMD) has said.

In its monthly weather outlook for May, released on its website on Wednesday, BMD also said there are possibilities of two to three days of moderate to severe thunderstorms with hails and three to five days of light thunderstorms with hails at places over the country in this month.

Rainfall is likely to be normal over the country throughout the month, it added.

On the other hand, one to three mild (36-37.9 degrees Celsius) to moderate (38-39.9 degrees Celsius) and one to two severe (more than 40 degrees Celsius) heat waves are likely to occur at places over the country in this month.

Day temperature is likely to be normal and night temperature is likely to be above normal over the country.

During the month of May, normal flow is expected in the major rivers of the country, BMD said.

However, due to isolated heavy rainfall, water levels in the rivers of the northern, north-eastern, and southern regions may rise at times.

BMD forecasts 16 to 19 days of rainfall in Dhaka division in this month, 18-21 days of rainfall in Mymensingh, 15-18 days in Chattogram, and 22-25 days in Sylhet division.

Besides, Rajshahi division may experience 14-17 days of rainfall, Rangpur 15-18 days, Khulna 14-16 days and Barishal 15-18 days this month.

The average daily evaporation may be 3-5mm and the average daily sunshine hour may be 5.5 to 7.5 hours in this month, it added.