In three and a half months since the third week of May, rough weather events, including heavy rains, squalls and high tides, prompted the Bangladesh Meteorological Department to issue a marine cautionary signal 13 times.
Back-to-back low pressures together with strong monsoon triggered the rough weather events, leading to frequent announcements of cautionary signal number three, with its direct and indirect consequences felt across Bangladesh.
The direct consequences saw strong waves and tides lashing Bangladesh’s coast, rivers rapidly swelling and frequently crossing their danger marks, and heavy rains abruptly disrupting life and business.
Well-off city dwellers mostly felt the rough weather consequences indirectly, in the high prices of Hilsa and vegetables.
“Bad weather greatly reduced Hilsa production. The sea remained rough so often that we could barely afford to go fishing,” said Al Amin, a fish trader based in Mohipur of Patuakhali.
Three trawlers that Al Amin recently sent for fishing in the Bay of Bengal returned in less than two days. The trawlers caught Hilsa worth Tk 5 lakh on average, a fifth of a regular seasonal production.
“Sea fishing accounts for at least 70 per cent of annual Hilsa production,” said Md. Anisur Rahman, a Hilsa researcher and former director at the Bangladesh Fisheries Research Institute.
Fishing usually requires farmers to travel 12 hours to the sea. In a recent field visit, officials at the Bangladesh Meteorological Department found that fishing by ordinary trawlers along the Bangladesh coast starts about 50km off the coast. The BMD’s forecast reaches a maximum distance of 57km off the coast.
Two of the latest low-pressure systems originated in the gap of less than two days. The last one formed on August 27 and dissolved on August 29.
Hilsa catching usually goes on in full swing in August, flooding the kitchen markets. Schools of Hilsa fish are expected to be swimming through sweet water along rivers and salt water along the coast in August. Hilsa season continues until the ban comes in October.
In the ongoing month alone, particularly after August 13, the BMD issued the cautionary signal four times. July saw the signal issued four times, June three times and May twice. The signals signified a great disruption in fishing, particularly after the universal ban on the activity for two months from March to April.
A cautionary signal could remain in effect from three to five days when heavy rain, wind rising up to 50 kmph and tide leaping up to five meters could occur, separately and simultaneously.
Such weather conditions prevailed on 39 to 65 days of roughly the last 100 days due to the interaction between wind and temperature in the Bay of Bengal, which is roughly 15 times the size of Bangladesh.
“The monsoon was rather strong this year and the overall weather condition was not comfortable for many people,” said Muhammad Abul Kalam Mallik, a senior meteorologist at the BMD.
Worse than Before?
Bangladesh this year saw the earliest onset of monsoon, which signifies a seasonal shift in wind flow, particularly from the south to the north, in four and a half decades. Since 1981, according to the Changing Climate of Bangladesh report released by the BMD in 2024, the monsoon arrived at Bangladesh’s coast in late May 11 times, eight of them occurring since 2000. Monsoon officially begins in June.
The influence of global warming on monsoons, which impact South Asian and Southeast Asian regions, is still being studied. Some studies indicated less generation of low-pressure systems in the Bay of Bengal due to global warming. The BMD’s changing climate study further corroborated a World Bank report stating that global warming was altering Bangladesh’s seasonal pattern.
Ten or more low-pressure systems formed in a single monsoon season only six times, according tolow-pressure data released by the BMD covering the years from 1981 to 2019. The highest 13 low-pressure systems formed during the monsoon of 1989.
The ongoing monsoon saw the generation of at least six low pressure systems with a month in the season still to go. The last monsoon month, which is September, historically sees more low-pressure systems compared with other monsoon months.
In April this year, the US-based private research university Massachusetts Institute of Technology predicted that monsoon and cyclone seasons would overlap due to changing climate, which will also unleash a once-in-a-century storm tide once every decade.
A low-pressure system, on the other hand, is born when more air rises, leading to low surface pressure. Scientists say increased temperature causes more air to rise while increasing the atmosphere’s capacity to hold water vapor.
Both monsoon and low-pressure systems move toward land, packed with rain, wind and tide.
Inside the Impact Zone
Frequent low pressures, with the potential to intensify into cyclones, could bear long-term consequences for the inhabitants of Bangladesh, a low-lying delta ranked as one of the most climate-vulnerable countries in the world.
Since the ongoing monsoon set in, low-pressure-triggered inclement weather breached levees, washed away houses and crops and frequently disrupted electricity supply to millions of people. Inclement weather during the period also frequently suspended waterway communication, swamped villages, cities and towns and caused hundreds to leave home to escape flash floods and landslides.
Though well-off citizens saw their livelihood intact despite bad weather, many of the poor, accounting for nearly a third of 171 million people, found it to be crippling. Livelihood requires the poor to go outside, whether they are farmers in villages or rickshaw pullers or transport workers or construction workers living in cities and towns.
Almost record-breaking rains swept parts of Bangladesh in June, with Teknaf, Bangladesh’s farthest southern land tip, recording more than 1,144mm of rainfall, which is slightly below its historical record of 1,290mm and more than four times the normal amount of rain expected in the first monsoon month, according to data released by the Flood Forecasting and Warning Centre. Khagrachhari’s Ramgarh and Feni’s Parshuram also recorded far higher than usual rainfall in the same month.
In July, the FFWC data showed, Teknaf witnessed over 1,384 mm of rainfall, slightly below the historical record of rain of 1,432mm and over four times the normal expected rain. Cox’s Bazar recorded 1,401 mm of rainfall against the month’s normal rainfall of about 945mm, while Noakhali witnessed 1,171mm of rainfall against the normal rainfall of about 739mm. Parshuram recorded 872 mm of rainfall against the month’s usual rainfall record of about 562mm.
On July 7, the FFWC reported, the Muhuri River swelled 509 cm in six hours until 3:00pm while the Belonia River rose 532cm in eight hours until 5:00pm.
Newspapers reported that the spell of heavy rainfall had continued for at least two more days, sinking many villages, towns and cities under up-to knee-deep water, and washing away houses, crops and fish enclosures. A flash flood struck Feni, Noakhali and Cumilla districts.
For many living along the coast, the July disaster came on the heels of the previous one that struck on May 30. Millions were left without electricity in 14 districts along the coast hit by heavy rains and high wind and tides.