Vietnam's Coffee Outlook Clouded by Weather Extremes, Irrigation Challenges, and Emerging El Niño Risks

CoffeeNetwork (New York) - Vietnam's coffee sector is entering a critical phase of development with weather conditions across the Central Highlands painting an increasingly mixed picture for the country's next robusta crop. While some producing areas are benefiting from improved moisture conditions following earlier dry weather, others are grappling with excessive rainfall, mounting pest and disease pressure, and concerns that irrigation shortages earlier in the season may have already constrained yield potential. Industry participants in several regions are now warning that production could decline by as much as 20% if adverse conditions persist into the remainder of the growing cycle.

The uncertainty comes at a time when global coffee markets remain heavily dependent on Vietnam, the world's largest robusta producer. Although Brazil's record crop has eased some supply concerns, traders continue to closely monitor weather developments in Vietnam because robusta inventories remain relatively tight and demand from the soluble coffee sector continues to expand. Any meaningful reduction in Vietnamese output could quickly alter the balance of the global robusta market.

Earlier Dry Conditions Raised Concerns Across the Coffee Belt

The challenges began earlier this year when many parts of Vietnam experienced below-normal rainfall during key stages of coffee development. Rainfall from January through mid-April was reported at 10% to 40% below historical averages, while river flows and reservoir levels across several watersheds declined significantly. The resulting water shortages raised concerns about flowering uniformity, cherry retention, and bean development across major producing provinces including Dak Lak, Dak Nong, Gia Lai, and Lam Dong.

Vietnam's Central Highlands account for roughly 90% of the nation's coffee output, making irrigation essential during the dry season. Unlike many arabica-producing regions that rely primarily on rainfall, intensive robusta production in Vietnam depends heavily on irrigation to trigger flowering and sustain cherry development.

Growers in several districts reported difficulty maintaining irrigation schedules as wells, reservoirs, and local waterways came under pressure. Agronomists note that moisture shortages during flowering can cause uneven blooming, while water stress during fruit set can lead to flower abortion and cherry loss. Once those losses occur, yield potential cannot be recovered later in the season.

The irrigation challenge is becoming increasingly structural rather than merely seasonal. Coffee producers throughout the Central Highlands face growing competition for water resources, declining groundwater levels caused by decades of intensive pumping, and increasingly erratic rainfall patterns. In provinces such as Gia Lai and Dak Nong, some producers have reportedly been forced to pump from greater depths, increasing fuel and electricity costs while reducing profitability. Smaller farms with limited access to reservoirs or modern irrigation systems remain particularly vulnerable.

Rain Has Returned, But New Risks Are Emerging

Ironically, the weather narrative has shifted dramatically over the past several weeks. Following concerns about drought and irrigation shortages earlier in the year, many coffee-growing areas are now experiencing above-average rainfall.

Recent weather assessments indicate that Dak Lak received rainfall more than 60% above long-term averages during August, while Lam Dong recorded precipitation nearly 35% above normal. At the same time, temperatures across the region have trended cooler than average, slowing cherry development and bean filling.

According to the latest forecasts, additional rainfall is expected across much of the Central Highlands. Vietnam's meteorological authorities recently warned of thunderstorms and localized heavy rainfall exceeding 70 millimeters in some areas, with elevated risks of flooding, landslides, and prolonged periods of canopy moisture.

While the additional moisture may alleviate some concerns about water availability, excessive rainfall introduces an entirely new set of production risks.

Pest and Disease Pressure Increases Under Wet Conditions

Heavy rainfall and persistent humidity are creating favorable conditions for fungal diseases and other crop health issues across Vietnam's coffee belt.

One of the primary concerns is coffee leaf rust, which thrives when leaves remain wet for prolonged periods. While many Vietnamese robusta varieties possess improved resistance compared with arabica cultivars, sustained humidity can still increase infection rates and weaken overall tree health. Excessive cloud cover associated with prolonged rainy periods may also reduce photosynthetic activity, limiting bean development and potentially reducing final bean weight.

Producers are also closely monitoring anthracnose, Cercospora leaf spot, berry diseases, and other fungal pathogens that proliferate during wet conditions. Disease outbreaks during the bean-filling stage can have a significant impact on quality, often resulting in higher defect counts, less uniform bean sizes, and lower export grades. These quality losses can sometimes be as important commercially as outright production declines.

Compounding the problem, excessive rainfall can make disease control more difficult. Fields may become inaccessible for spraying, while heavy precipitation can wash away fungicide applications before they become fully effective.

Agronomists also warn that trees weakened by earlier drought stress are often more susceptible to disease outbreaks once wet weather arrives. This dynamic may prove particularly important in 2026, as many coffee-growing areas experienced both moisture deficits and irrigation challenges earlier in the season before transitioning into a wetter pattern.

El Niño Adds Another Layer of Uncertainty

Perhaps the most significant medium-term threat facing Vietnam's coffee sector is the emergence of El Niño conditions.

Vietnam's meteorological agencies have confirmed that El Niño has developed in the Pacific and could intensify during the second half of 2026 and into 2027. Some forecasts suggest the event could become among the strongest observed in decades, prompting warnings about future water shortages across the country's key agricultural regions.

Historically, El Niño events have been associated with hotter-than-normal temperatures and below-average rainfall across much of Vietnam. For coffee growers, that generally translates into higher irrigation demand, reduced soil moisture, and elevated risk during critical growth stages.

During flowering, prolonged drought can lead to scattered and uneven blooms rather than the synchronized flowering required for maximum productivity. During cherry development and bean filling, moisture shortages can reduce bean size, increase cherry losses, and ultimately lower yields. Severe drought can also impair cup quality by reducing bean density and increasing defects.

Authorities have already identified the Central Highlands as one of the regions most vulnerable to irrigation shortages if El Niño continues to strengthen through the upcoming dry season. Forecasts point to warmer-than-normal temperatures and the possibility of significant rainfall deficits extending into early 2027.

Yet El Niño's impact is not always straightforward. Vietnamese meteorologists emphasize that strong El Niño years can also produce episodes of torrential rainfall, flash flooding, and weather instability. As a result, producers may face alternating periods of drought and excessive moisture rather than a simple dry-weather scenario. This combination can create greater uncertainty for both yield forecasts and quality expectations.

For the coffee market, the greatest concern may be the increasing volatility of Vietnam's weather rather than any single threat. The emerging pattern suggests producers are confronting multiple overlapping risks: structural irrigation constraints, early-season drought stress, elevated disease pressure from excessive rainfall, and the possibility of a strengthening El Niño during the next dry season. Any one of these challenges alone might be manageable. Combined, they increase uncertainty surrounding both production volume and bean quality.

Alexis Rubinstein

Sources: National Center for Hydrometeorological Forecasting, Vicofa, NOAA