According to an update from the National Centre for Hydro-Meteorological Forecasting (NCHMF), the 2026-2027 El Nino continues to strengthen, with sea surface temperatures in the NINO3.4 region about 2°C above the long-term average in the second week of September.

From October to December 2026, El Nino is expected to be at a very strong intensity, with a 98% probability, and could reach its peak. From January to March 2027, the phenomenon is forecast to stay very strong, although its probability and intensity are set to gradually decline. The weather agency has not ruled out El Nino persisting into the early summer of 2027.

Warmer winter, earlier heatwaves

In Vietnam, the effects of El Nino are likely to become more pronounced in the coming months, particularly through higher temperatures, heatwaves, drought and water shortages, especially in the dry season.

The national weather bureau reported that cold-air activity is set to be weaker than normal in the 2026-2027 winter, with severe cold spells likely to occur later and less frequently than the long-term average. Average temperatures nationwide are forecast to be 1-2.5°C above the long-term average.

From early 2027, heatwaves could occur earlier across the country. In summer months, heatwaves are predicted to be intense, with more hot days than the long-term average and more than in 2026. The weather bureau has not ruled out temperatures exceeding previous records.

Rainfall from now until the end of 2026 would be below the long-term average across much of the country, particularly in the South-central Coast, Central Highlands and southern region, with deficits generally ranging from 20-40%. The rainy season in these areas could also end earlier.

The same areas are likely to receive less rainfall in early 2027. Higher temperatures and earlier heatwaves could increase water demand and evaporation, putting additional pressure on water resources.

As a result, the risk of drought, water shortages and saltwater intrusion in the South-central Coast, Central Highlands and southern region is assessed as very high during the dry season in early 2027.

Fewer storms do not rule out extreme rainfall and floods

El Nino can alter atmospheric circulation, affecting rainfall patterns as well as the activity of storms and tropical depressions.

From now until the end of 2026, the number of storms and tropical depressions over the East Sea and those affecting mainland Vietnam is forecast to be lower than the long-term average. However, fewer storms do not mean that strong storms will not occur, and below-average rainfall does not rule out extreme rainfall events.

During strong El Nino events, episodes of very heavy rainfall, floods, flash floods, landslides or storms with complex developments can still occur. These events are also influenced by regional-scale weather systems and atmospheric conditions at specific times.

Therefore, the El Nino signal alone cannot be used to accurately predict a specific natural disaster in a particular locality. The level of impact depends on interactions between El Nino and atmospheric and oceanic conditions, as well as weather patterns in different periods and seasons.

With El Nino already at a very strong intensity and showing a potential for further strengthening, the weather bureau has advised localities to prepare for both groups of risks: heatwaves, drought, water shortages and saltwater intrusion that could persist throughout the 2026-2027 dry season, as well as extreme rainfall, storms, floods and other extreme weather events that could occur at specific times.

Experts warn of cardiovascular risks as El Nino fuels prolonged heatwaves

As El Nino is forecast to intensify and persist through the end of the year, experts have warned people not to underestimate the health impacts of extreme weather, particularly on the cardiovascular system.