The warning is particularly serious because dry and hot conditions have already emerged unusually early in 2026. Across much of the country, rainfall from the start of the year through mid-April has already fallen 10–40 percent below long-term averages, while river flows and water levels in multiple major basins have dropped to some of the lowest levels recorded for the same seasonal period. These early deficits suggest that Vietnam may already be entering a vulnerable hydrological cycle even before El Niño fully develops.

If El Niño strengthens according to current projections, national average temperatures are expected to rise above normal, with more frequent, longer-lasting, and more intense heatwaves than in 2025. Rainfall deficits could worsen significantly, especially from late 2026 into early 2027, with precipitation reductions ranging from 2 percent to as much as 50 percent in some areas. The rainy season may also end earlier than usual, shortening critical water recharge periods for rivers, reservoirs, and groundwater systems.

This scenario poses major risks for national water infrastructure. Large reservoir systems, particularly in the Da River basin, may experience inflow shortages of 10–25 percent between May and July 2026 compared to historical averages. Such deficits could affect downstream water supply for agriculture, urban consumption, and hydropower generation—raising concerns not only about food security but also energy security.

The most vulnerable regions are expected to include South Central Vietnam, the Central Highlands, and the Mekong Delta, where drought and saltwater intrusion could intensify during the 2026–2027 dry season. In these regions, reduced freshwater availability may severely impact crop production, household water access, and ecological stability. Early 2027 could see particularly broad water shortages if mitigation measures are delayed.

Importantly, El Niño does not simply mean “less rain.” Experts warn that even in overall drier years, short bursts of extreme rainfall may still occur, increasing risks of flash floods, landslides, and urban flooding. Tropical storm activity in the East Sea may decline overall, but stronger, less predictable storms remain possible.

This complex climate outlook means Vietnam must prepare for both scarcity and extremes simultaneously. Water resource planning, reservoir management, drought-resistant agriculture, salinity barriers, wildfire prevention, and public awareness campaigns will all become increasingly important.

Ultimately, early warning is Vietnam’s greatest advantage. Recognizing El Niño risks months in advance creates a critical window for proactive adaptation rather than reactive crisis response. By strengthening climate forecasting, protecting strategic water reserves, adjusting crop systems, and improving regional preparedness, Vietnam can reduce the potential social and economic damage of a severe El Niño cycle.

In this context, El Niño is not simply a weather pattern—it is a national resilience test. The decisions made in 2026 may determine how effectively Vietnam protects its water security, agricultural stability, and climate resilience through one of its most challenging environmental periods ahead.