August 6, 2025
DHAKA – This July has been wetter than previous years because of three bouts of low pressure that Bangladesh experienced. Rainfall was 23.5 percent higher in the past month than the historical average for July.
While the national average precipitation for July is is 457mm, this year it was 564 mm. Barishal division recorded the highest rain with 878 mm while Rangpur division was lowest with 253 mm.
The Bangladesh Meteorological Department explained that Bangladesh experienced three low-pressure systems on July 7, July 14 and July 24 which led to heavy rain.
“Due to active monsoon, influence of low pressure and depression heavy to very heavy rainfall occurred at some places over the country in this month,’ said BMD’s climate outlook.
Dr Abul Kalam Mallik said that monsoon was very active this year.
Along with the active monsoon, the low-pressure systems (LPS) in the Bay of Bengal cause excess rainfall when it crosses onto land, Dr Mallik said.
The BMD outlook forecasts one or two low pressures in August, one of which may intensify into a depression.
Asked, Dr Rashed Chowdhury, an eminent climate scientist, said an active monsoon, coupled with warmer sea surface temperatures leading to higher evaporation caused the heavy rainfall in July.
He said, higher evaporation meant it was feeding moisture-laden winds and strengthening the monsoon system.
Climate scientist Rashed Chowdhury, adjunct faculty at Arizona State University said the recent shift of the Indian Ocean Dipole (IOD) and Madden-Julian Oscillation (MJO) was causing the huge rainfall.
He said, shift of negative IOD enhances moisture inflow and intensifies rainfall over the Bay.
“When the IOD is negative, warmer sea surface temperatures in the eastern Indian Ocean increase evaporation, boost moisture inflow, and strengthen monsoon winds,” said Dr Chowdhury.
The Madden–Julian Oscillation (MJO) increases tropical convection, potentially leading to heavier rainfall and more active monsoon conditions over Bangladesh.
He said an active MJO acts like a “large-scale rainmaker” over the Bay of Bengal and South Asia.
“It intensifies rainfall, strengthens monsoon winds, and destabilises the atmosphere—conditions that make heavy rain and flooding more likely,” he said.
Dr Rashed also said, currently the several climatic models confirm that a 41 percent probability of La Niña developing while the likelihood of El Niño remains low, at less than 15 percent.
If La Niña develops while El Niño remains weak, Bangladesh is likely to experience above-average monsoon rainfall, increasing the risk of flooding and waterlogging, particularly in low-lying and riverine areas.