Over the next four weeks, Bangladesh's major river systems are on track for one of the most significant flood events of the 2025 monsoon season. Our current window of concern runs from roughly August 15 through September 10, with the Padma, Jamuna, Tista, and Brahmaputra basins all showing elevated risk.

Three signals are converging:

1. Twin monsoon depressions in the Bay of Bengal

Over the remaining 20 days of August, ensemble guidance from ECMWF and NOAA GFS suggests two back-to-back low-pressure systems forming over the northern Bay of Bengal. Each would push heavy rainfall onto already-saturated ground in the catchment zones of Assam, West Bengal, and northern Bangladesh.

2. Upstream catchments are running near capacity

Satellite soil-moisture readings across Assam and the eastern Himalayan foothills have been in the 90th–95th percentile for this time of year. When catchments are this saturated, additional precipitation doesn't infiltrate. It runs off directly into the Brahmaputra and Ganges systems, arriving in Bangladesh within 24–48 hours.

3. Astronomical tides compound the coastal backflow

The spring-tide alignment during the final week of August raises downstream sea levels in the Meghna estuary. That elevated downstream level slows river discharge at the coast, causing water to back up into Barisal, Noakhali, and parts of Chittagong.

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Stations to watch. Jamuna at Bahadurabad and Sirajganj; Brahmaputra upstream inflows from Dhubri; Tista discharge from Gajoldoba; Padma/Ganges flow from Farakka. Gauges crossing their respective danger levels are early indicators of 48–72-hour downstream flood arrival.

Who is most exposed

  • Riverine char communities: first to be inundated and last to drain; displacement risk is highest.
  • Sylhet haor region: already absorbing heavy upstream rainfall; flash-flood thresholds are within 10–15 cm of this year's earlier crest.
  • Boro rice storage: post-harvest storage in low-lying areas is vulnerable to sudden inundation.
  • Urban stormwater zones in Dhaka, Chittagong, and Sylhet city: rain falling during the peak window can exceed drainage capacity in under 60 minutes.

What we'll publish next

As the forecast horizon tightens, Abohawabid and yvortex will issue daily outlooks with district-level probabilities, gauge updates for the four key rivers, and upazila-specific advisories for farming and evacuation decisions. If you're coordinating emergency response, get in touch. We can provide raw data feeds.