Nature hints at early monsoon onset

The country is scorching in extreme heat as a heatwave sweeps across almost the entire nation, leaving everyone gasping for relief. Amidst this, the meteorological office has brought good news, forecasting an early arrival of the monsoon along with a easing of the ongoing heatwave.

According to the Bengali calendar, the two months of Asharh and Shrabon are known as the monsoon season. Generally, the monsoon officially begins in the country with the entry of the southwest monsoon winds. However, this time, the Bangladesh Meteorological Department has announced the arrival of the monsoon ahead of its usual schedule. The Dhaka Meteorological Office informed Views Bangladesh that the monsoon winds may enter Bangladesh through the Teknaf coast by June 10 (even before the official start of the monsoon season) and could spread across the entire country by June 16.

Meteorologist A.K.M. Nazmul Haque told Views Bangladesh that due to the active state of La Niña, the southwest monsoon is entering Bangladeshi territory slightly ahead of its usual schedule this year. According to him, the monsoon could spread its influence across most parts of the country by the second week of June.

"La Niña" is playing a major role in this situation. It is the opposite climatic condition of "El Niño." When La Niña is active, it alters the normal wind patterns over the Pacific Ocean, pushing warm surface water westward. As a result, relatively cold water from the deep ocean rises to the surface, causing sea surface temperatures in the eastern Pacific Ocean to drop below normal.

Meanwhile, Mostofa Kamal Palash, a weather and climate researcher at the University of Saskatchewan in Canada, shared an update on his verified Facebook post on June 3. According to the latest data from the weather forecast models of the European Union and the United States, the southwest monsoon will enter Bangladesh through the Teknaf coast in the second week of June. Following this, the monsoon will sequentially spread to Cox's Bazar, Chattogram, Barishal, Khulna, Cumilla, Dhaka, Sylhet, Mymensingh, Rajshahi, and Rangpur regions, gradually becoming fully active.

He further mentioned that once the monsoon becomes active, relatively heavier rainfall may occur in the districts of Chattogram, Cox's Bazar, Feni, Jashore, Satkhira, Khulna, Jhenaidah, Faridpur, Madaripur, Gopalganj, Magura, Rajbari, Manikganj, Munshiganj, Barguna, Barishal, Pabna, Sirajganj, Jamalpur, Tangail, Mymensingh, Netrokona, Sunamganj, and Sylhet. Meanwhile, the influence of the pre-monsoon winds has already begun in the country. As a result, there is a possibility of rainfall in various regions, including the capital Dhaka, within the next few days. Simultaneously, the ongoing heatwave is expected to ease.

According to meteorologists, while El Niño is generally responsible for heatwaves and dry weather, La Niña plays a supportive role in increasing rainfall. Under its influence, the possibility of an early monsoon and slightly higher-than-normal rainfall arises. Since the impact of La Niña is relatively more active this year, there are indications of a shift in the normal weather cycle. Consequently, signs of an early monsoon are visible not only in Bangladesh but across the entire Indian subcontinent. In addition, monsoon rains are expected to start ahead of schedule in Myanmar, Thailand, Malaysia, Indonesia, Laos, and Vietnam as well.

On the other hand, meteorologist Khondokar Hafizur Rahman states, "Due to climate change, variations are being observed in the usual schedule of the monsoon's arrival and departure. Global warming, changes in sea surface temperatures, and atmospheric instability are the primary reasons for this. As the Earth's average temperature rises, atmospheric pressure and wind flow trajectories are changing. Since the water temperature of the Bay of Bengal is higher than normal, the monsoon winds have strengthened rapidly. Simultaneously, the influence of the active La Niña in the Pacific Ocean has helped bring the monsoon forward." Regarding the potential impact of an early monsoon, he notes that while it could bring relief to farmers—especially since Boro rice farmers can minimize damage risks if they harvest their crops on time—excessive rainfall or untimely heavy downpours could pose new risks to agriculture.

He warns that due to the early monsoon, river water levels could rise rapidly, leading to flash floods. The risk of landslides in hilly areas could increase, and the possibility of cyclones cannot be ruled out either. Furthermore, even if the monsoon begins early, there is no guarantee it will end early. Rather, if the monsoon season is prolonged, the risk of long-term flooding could intensify. However, he also opines that if the rainfall remains at a normal level and abnormal downpours do not occur, an early monsoon could yield positive outcomes for nature and agriculture.

Meanwhile, the monsoon has also arrived in neighboring India. The monsoon season officially began in the country on Thursday (June 4) as the southwest monsoon entered through the Kerala coast. The India Meteorological Department (IMD) stated that favorable conditions have been prevailing since June 4 for the advancement of the monsoon over Kerala and its neighboring regions. As a result, widespread rainfall has already started in various areas of the state.

Experts believe that under the influence of the monsoon actively developing over both India and Bangladesh simultaneously, the amount of rainfall across South Asia this season could be slightly higher than normal. Consequently, while this will bring relief from the heatwave, taking early preparations to tackle disasters like floods and landslides has also become crucial.