Deep Depression in Bay of Bengal Triggers Nationwide Five-Day Rainfall

The Bangladesh Meteorological Department (BMD) has issued a five-day weather outlook predicting light to moderate and localized heavy to very heavy rainfall across all eight administrative divisions of the country. The prolonged wet spell is being driven by a seasonal low-pressure system over the North-west Bay of Bengal and adjacent areas, which has intensified into a deep depression.

According to a weather bulletin released on Monday (27 July) by BMD meteorologist Khowondokar Hafizur Rahman, the active monsoon condition is expected to persist over the next 120 hours. The system is anticipated to lower day and night temperatures across the nation during the initial stages before a slight rise later in the week.

Detailed Meteorological Forecast

The weather office has outlined a day-by-day progression for the meteorological conditions spanning 27 July through 31 July:

• Monday to Tuesday Morning (27–28 July): Most places in Rajshahi, Dhaka, Khulna, Barishal, and Chattogram divisions, alongside scattered areas in Rangpur, Mymensingh, and Sylhet, are expected to experience light to moderate rain or thundershowers accompanied by temporary gusty winds. Moderately heavy to heavy falls are likely at isolated locations nationwide. Both day and night temperatures are expected to drop slightly.

• Tuesday to Wednesday Morning (28–29 July): Rain and thundershowers with gusty winds will likely cover most parts of Khulna, Barishal, Chattogram, and Sylhet divisions, as well as several areas in Rangpur, Rajshahi, Dhaka, and Mymensingh. Heavy rainfall risks remain across isolated pockets, with temperatures continuing their slight downward trend.

• Wednesday to Thursday Morning (29–30 July): Precipitation is forecasted to become widespread, affecting most places across all eight divisions: Rajshahi, Rangpur, Dhaka, Mymensingh, Khulna, Barishal, Chattogram, and Sylhet. Daytime and night-time temperatures are expected to remain largely unchanged.

• Thursday to Friday Morning (30–31 July): Rainfall activity will continue in many regions across all eight divisions. Heavy to very heavy downpours remain possible in isolated areas. Temperatures across the country are projected to register a marginal increase.

• Friday to Saturday Morning (31 July–1 August): Rainfall will remain dominant over most places in Rangpur, Mymensingh, Chattogram, and Sylhet divisions, and many areas across Rajshahi, Dhaka, Khulna, and Barishal divisions. Overall temperatures are expected to stay stable.

Background and Regional Context

Deep depressions forming in the Bay of Bengal during the peak monsoon season typically bring sustained rainfall, choppy sea conditions, and sudden wind gusts to South Asia. In coastal regions, maritime ports are routinely advised to hoist cautionary signals to ensure the safety of fishing trawlers and commercial vessels operating offshore.

Monsoon-induced torrential rains frequently lead to urban waterlogging in major metros like Dhaka and Chattogram, whilst heightening the risk of landslides in the hilly terrains of the south-east. Authorities generally urge maritime operators to remain close to the coast and advise citizens in vulnerable areas to take necessary safety precautions during prolonged periods of heavy precipitation.