Higher Temperatures and Below-Average Rainfall Forecast for June

The long-term forecasting expert committee of the Bangladesh Meteorological Department (BMD) has announced that temperatures across the country are expected to remain above normal throughout June. Concurrently, the total accumulated precipitation for the month is projected to be slightly lower than seasonal averages. Md Mominul Islam, the Director (Current Charge) of the BMD and Chairman of the expert committee, stated that the south-west monsoon, which marks the onset of the official rainy season, is expected to advance across the country during the first half of June. However, despite the seasonal arrival of the monsoon, total rainfall throughout the month is forecast to remain below typical levels.

Projections for Heatwaves and Divisional Rainfall

According to the expert committee, both daytime and nocturnal temperatures are forecast to exceed long-term monthly averages. The meteorological assessment indicates that different regions of the country are likely to experience two to three mild-to-moderate heatwaves. The statistical thresholds defined by the BMD for heatwaves, alongside the specific quantitative rainfall projections across individual administrative divisions for June, are structured in the table below:

Current Weather Systems and Monsoon Trajectory

Md Shahinul Islam, a meteorologist at the BMD’s Storm Warning Centre, reported that while scattered rainfall has commenced in several regions, it remains insufficient to substantially mitigate the ongoing heatwave. Precipitation has been recorded in parts of Rangpur, Bogra, Rajshahi, and Netrokona, resulting in minor, localised temperature drops. However, a complete mitigation of the widespread heatwave across the country is expected to require an additional two to three days. Furthermore, the capital city of Dhaka has not yet received significant rainfall, causing the oppressive heat to persist. The monsoon system is currently situated near the coast of Myanmar and is projected to take approximately three to four days to fully enter Bangladesh.

The long-term outlook for June also predicts five to seven days of mild-to-moderate thunderstorms accompanied by lightning. Additionally, one to two low-pressure systems are anticipated to develop over the Bay of Bengal, with one potentially intensifying into a monsoon depression.

Retrospective Analysis of May Weather and River Systems

Meteorological data compiled by the BMD shows that the country recorded an average of 289 mm of rainfall during the month of May, representing an increase of 7.4% above seasonal norms. Divisional analysis indicates that Dhaka, Mymensingh, Sylhet, Rajshahi, and Rangpur observed above-average rainfall, whereas the Chittagong, Khulna, and Barisal divisions experienced a deficit relative to normal levels. The highest single-day precipitation in May occurred on 13 May in Dinajpur, where 144 mm of rainfall was logged. This widespread moderate-to-heavy, and occasionally very heavy, rainfall was driven by the convergence of western low-pressure systems and easterly winds, which also triggered lightning strikes, gusty winds, and isolated hailstorms.

In contrast, May also saw several spells of mild heatwaves across various regions. The maximum temperature for the month reached 38.0°C, recorded on 18 May in Chuadanga, while the minimum temperature dropped to 18.4°C on 3 May in Sylhet. Cumulatively, the country’s overall average temperature for May remained 0.4°C lower than the long-term normal.

Regarding hydrological conditions, the forecast indicates that water flow in the major river systems is expected to remain stable within normal parameters. Nevertheless, isolated heavy downpours in the northern, north-eastern, and south-eastern regions may cause temporary water level rises in certain rivers.