April in Bangladesh has long been synonymous with scorching heat, prolonged dry spells and occasional nor’westers sweeping across the plains.
Traditionally regarded as the country’s warmest month, it is more often associated with heatwaves than sustained rainfall.
But April-May 2026 has disrupted that familiar pattern.
Frequent thunderstorms, hailstorms and intense downpours turned this year’s pre-monsoon season into one of the wettest Aprils Bangladesh has experienced in recent years, underscoring what meteorologists and climate experts describe as a growing shift toward more erratic and extreme weather patterns.
According to data from the Bangladesh Meteorological Department (BMD), the country recorded 75.7% more rainfall than normal during April — the highest for the month in the past five years. Besides, May is also following the same pattern.
Experts say the unusual rainfall trend reflects broader climate-related changes unfolding across South Asia, where warming oceans and increasingly unstable atmospheric systems are intensifying both droughts and heavy rainfall events.
BMD data shows two major rainfall episodes — between April 6-9 and April 26-30 — brought moderate to extremely heavy rainfall to large parts of Bangladesh.
On April 28, Nikli in Kishoreganj recorded 160 millimetres of rainfall in a single day, among the season’s highest one-day April totals.
Sylhet division experienced the heaviest rainfall nationwide, recording an average of nearly 603 millimetres throughout the month. Dhaka received an average of 213 millimetres, while Rajshahi saw the lowest rainfall at 78 millimetres.
Meteorologist AKM Nazmul Haque said rainfall anomalies were particularly striking in several regions.
“Rainfall in Dhaka was nearly 80% above normal levels. In Mymensingh, rainfall increased by almost 100%, while Sylhet recorded more than double its seasonal average,” he told Dhaka Tribune.
According to him, the combined influence of active western troughs, moisture-laden winds from the Bay of Bengal and unusually high atmospheric humidity created repeated episodes of atmospheric instability across the country.
Meteorologists say the interaction between relatively dry western air and warm, humid air flowing inland from the Bay of Bengal played a crucial role in triggering severe weather systems.
A senior BMD meteorologist explained that these contrasting air masses generated powerful cumulonimbus clouds — towering storm clouds capable of producing intense thunderstorms, hail and short-duration heavy rainfall.
“These cloud systems generated frequent thunderstorms, nor’westers and intense rain events throughout April,” he said.
The BMD recorded an average of nine thunderstorm days during the month. While the number itself was not exceptionally high, experts noted that the continuity and intensity of the storm systems were unusual.
Nazmul Haque said above-normal sea surface temperatures in the Bay of Bengal further intensified the situation by increasing evaporation and moisture accumulation in the atmosphere.
“Warmer air holds more moisture. When moisture-rich air rises and cools rapidly, it condenses into heavy rainfall. We observed that process repeatedly throughout April,” he said.
He also pointed to instability in the upper atmosphere as an additional factor behind the extreme rainfall pattern.
“Changes in upper-level atmospheric positioning and stronger convection systems enhanced cloud formation this year, significantly increasing the likelihood of intense rainfall events,” he added.
Climate scientists warn that Bangladesh is increasingly experiencing the defining characteristics of climate change: unpredictable seasonal behaviour and more frequent extreme weather events.
The Intergovernmental Panel on Climate Change (IPCC) has repeatedly highlighted that rising global temperatures increase the atmosphere’s moisture-holding capacity, making extreme rainfall events more likely.
Similarly, the World Meteorological Organization (WMO) has identified South Asia as one of the world’s most climate-vulnerable regions, where warming oceans are amplifying rainfall variability, heatwaves and severe storms.
Dr Mohammad Shamsuddoha, chief executive of the Center for Participatory Research and Development (CPRD), said the changing behaviour of Bangladesh’s pre-monsoon season reflects a wider climate crisis.
“Bangladesh contributes very little to global carbon emissions, yet it remains among the countries most vulnerable to climate change impacts. The abnormal shift in pre-monsoon rainfall patterns is part of that climate reality,” he said.
Rafa Khatun, assistant director of the Center for Climate Change and Environmental Research (C3ER), warned that excessive rainfall is no longer solely a meteorological concern.
“It is becoming a major challenge for agriculture, urban management, public health and food security,” she said.
The heavy rainfall has already disrupted agricultural activities in low-lying haor regions, where farmers are harvesting Boro rice.
Abdul Quddus, a farmer from Nikli haor in Kishoreganj, said repeated rainfall has delayed harvesting and heightened fears of crop losses.
“The rice is ready, but we cannot enter the fields because of continuous rain. If storms destroy the crops now, an entire year’s income will vanish,” he said.
Agricultural experts warn that untimely rainfall and hailstorms are increasingly disrupting traditional crop calendars, exposing rural communities to new climate-related vulnerabilities.
Urban areas are also feeling the strain.
Dhaka and several other cities experienced severe waterlogging, traffic congestion and localized power disruptions following short but intense rainfall events, exposing longstanding weaknesses in urban drainage systems.
Urban planners say most Bangladeshi cities remain inadequately prepared for climate-induced extreme rainfall.
Experts argue that without stronger adaptation measures — including climate-resilient drainage infrastructure, improved forecasting systems and sustainable urban planning — the economic and social costs of extreme weather are likely to rise sharply in the coming years.
The Meteorological Department expects above-normal rainfall and continued thunderstorm activity through May as moisture flow from the Bay of Bengal intensifies ahead of the monsoon.
Meteorologists believe Bangladesh may be entering a new climatic phase in which pre-monsoon months become increasingly volatile, marked by alternating heatwaves, severe storms and sudden extreme rainfall.
For one of the world’s most climate-vulnerable nations, the unusually wet April of 2026 may no longer be viewed as an isolated anomaly — but rather as a warning of the climate future already unfolding.