At midday on September 9, the National Centre for Hydro-Meteorological Forecasting said cold air had begun affecting northern Vietnam, while weather systems were emerging over the East Sea that could bring prolonged heavy rain to central regions in the coming days.
The meteorological agency forecast that around September 12-13, a tropical convergence zone was highly likely to generate a tropical depression in the central East Sea, with a probability of 70-80 per cent.
The tropical depression could then strengthen into a storm, with a probability of about 30-40 per cent. Notably, if a tropical depression or storm forms, its interaction with cold air and the tropical convergence zone could trigger a widespread spell of heavy rain across central Vietnam, lasting until around September 17.
The agency warned that this bout of rain carried a high risk of whirlwinds, lightning, flash floods, landslides and localised flooding.
For rainfall developments in the coming days, the National Centre for Hydro-Meteorological Forecasting outlined two scenarios.
Early-season cold air is affecting northern Vietnam (Photo: Manh Quan).
The more likely scenario, with a probability of 60-70 per cent, is that heavy rain will begin on September 10 and last until around September 16. The heaviest rainfall is forecast from Ha Tinh to Gia Lai.
Under the other scenario, with a probability of 30-40 per cent, the heavy rain could begin later, around September 14, and continue until September 17, focusing on the area from Nghe An to Hue.
The new spell of rain is forecast as many parts of central Vietnam and the Central Highlands have already seen heavy rainfall in recent days.
According to the meteorological agency, the 2026 storm season is expected to see fewer storms and tropical depressions over the East Sea than the multi-year average.
However, strong storms with complex developments may still occur. From September to December, areas affected by storms and tropical depressions are expected to gradually shift southwards towards central Vietnam and southern provinces and cities.