Bangladesh Meteorological Department has forecast an increase in rainfall and thunderstorms across the country as the southwest monsoon has advanced up to Barishal, Chattogram and Sylhet divisions, with conditions becoming favourable for its further spread nationwide within the next three to four days.

In its 24-hour weather bulletin issued on Monday evening, meteorologist Md Shahinul Islam said light to moderate rain or thundershowers accompanied by temporary gusty winds are likely in many parts of Chattogram and Sylhet divisions, while some areas in Rangpur, Mymensingh, Dhaka and Barishal and a few places in Rajshahi and Khulna divisions may also experience rainfall.

It also warned of moderate to heavy rainfall at isolated places across the country. Day and night temperatures may rise slightly during this period.

For the following 24 hours till Wednesday evening, the forecast suggests that Mymensingh and Sylhet divisions may experience rainfall in many places, while Dhaka, Khulna, Barishal and Chattogram divisions may see rain in several areas. Rain or thundershowers are also likely at a few places in Rangpur and Rajshahi divisions, with moderate to heavy rainfall continuing in some areas. Temperatures are expected to remain nearly unchanged.

According to the Met Office, the highest rainfall in the past 24 hours was recorded at 96 millimetres in Sylhet. The highest temperature was 37.2°C in Rajshahi, while the lowest was 25.5°C recorded in Kumarkhali and Koyra of Khulna division.

The Met Office said a trough of low pressure extending from West Bengal to the northwestern Bay of Bengal is influencing the current weather pattern, creating favourable conditions for increased rainfall across the country.