El Niño warning intensifies as India’s potato season approaches

WMO now sees a near-100% probability that the event will persist into early 2027, while India enters the run-up to its main potato crop with depleted monsoon moisture.

By Lukie Pieterse, Editor/Publisher of Potato News Today

Only days after Potato News Today published its global assessment of El Niño-related potato risks last week, the international climate warning has strengthened—and conditions in India have become more concerning.

On 3 September, the World Meteorological Organization said El Niño was firmly established and expected to develop into a very strong event before peaking towards the end of 2026. WMO’s forecasting centres now indicate a near-100% probability that El Niño will persist through February 2027.

That represents a significant hardening of the outlook described in PNT’s 2 September report. That article cited the US Climate Prediction Center’s assessment that El Niño had a greater than 90% chance of becoming very strong during the Northern Hemisphere autumn and winter.

The central conclusion of the earlier report remains unchanged: El Niño will not produce the same weather in every potato-growing region, nor can every drought, flood or heatwave be attributed to it. But the probability of a prolonged and exceptionally strong event is now clearer, increasing the importance of regional monitoring and preparation.

Pacific warming accelerates

According to WMO, the widely monitored Niño 3.4 sea-surface temperature anomaly averaged approximately 1.5°C above normal during May–July 2026 and reached 2°C in July. Weekly readings increased further between late July and mid-August, ranging from approximately 2.2°C to 2.6°C above average.

WMO’s September–November global seasonal outlook projects an ensemble-average Niño 3.4 anomaly of approximately 3.6°C, with the intensification trajectory expected to peak during November or December.

The organisation described the probability of El Niño continuing through February as an “exceptionally high likelihood of nearly 100%”.

Exceptionally warm water has also accumulated beneath the surface of the tropical Pacific. In some areas, WMO reported subsurface temperatures more than 8°C above average during July and early August. The combination of surface warming, deep ocean heat and reinforcing atmospheric signals is providing forecasters with unusually high confidence that the event will persist into 2027.

For potato producers, this does not constitute a yield forecast. It does, however, increase confidence in the underlying climate driver that may alter rainfall, temperature, disease pressure and water availability across several production regions during the coming months.

A global warning, not a universal weather forecast

WMO’s models favour above-normal temperatures across almost all land areas during September–November, together with rainfall patterns displaying what the organisation calls a pronounced atmospheric response to the strong Pacific warming.

The agency nevertheless emphasises that a very strong El Niño does not automatically produce equally severe consequences in every country.

Location, season and other climate influences remain decisive. WMO expects a positive Indian Ocean Dipole to develop during September–November, while waters in the tropical Atlantic are also forecast to remain warmer than normal. These conditions could strengthen, weaken or alter the familiar regional effects associated with El Niño.

This distinction is especially important for the potato industry. Heat during tuber initiation can produce a very different outcome from heat shortly before vine kill. A wetter season may support crop establishment in one district while causing waterlogging, late blight pressure and harvest delays in another.

An intense El Niño changes the odds. It does not determine the result in an individual field.

India’s monsoon deficit deepens

The most immediate new potato-related concern is India, where the southwest monsoon has weakened further ahead of the country’s main winter potato season.

When PNT published its earlier analysis, nationwide monsoon rainfall was running approximately 13% below normal and was expected to finish around 15% below the long-term average.

India subsequently ended August with rainfall 16% below normal for the month, according to figures from the India Meteorological Department reported by The Indian Express. Cumulative rainfall through August stood at only 84% of normal.

The geographical spread of the deficit is notable. Of the 741 districts monitored by IMD, 312—or 42%—had received deficient rainfall by the end of August. A further 38 districts, representing 5%, were classified as experiencing a large deficiency.

The southern peninsula recorded an August shortfall of more than 27%. Central India and the eastern and northeastern region each finished approximately 16% below normal, while northwestern India was around 10% below normal.

Bihar, one of India’s important potato-producing states, recorded a rainfall deficit of 40% by the end of August. Conditions nevertheless remain uneven: IMD indicated that parts of Bihar, eastern Uttar Pradesh, Odisha and several neighbouring areas could receive normal rainfall during September, even as below-normal rainfall was favoured across most of the country.

IMD Director General Mrutyunjay Mohapatra said September rainfall was expected to remain below 91% of the long-period average. This could leave rainfall for the full June–September monsoon season below 90% of normal.

Reuters reported on 4 September that such an outcome could make the 2026 monsoon India’s weakest in nearly two decades.

Why this matters for potatoes

India’s immediate monsoon damage is being observed primarily in summer crops such as rice, maize, soybean, cotton and pulses. The country’s main potato crop has not yet developed sufficiently for a credible national yield-loss estimate.

The potato risk lies in what the monsoon leaves behind.

September rainfall contributes to residual soil moisture, reservoir storage and groundwater recharge before much of the winter crop is planted. A weak end to the monsoon could therefore raise irrigation demand during potato establishment and early development.

Above-normal autumn temperatures would compound that pressure by increasing evaporation and crop water requirements. If excessive warmth extends into tuber initiation, it could also interfere with tuber formation and reduce the time available for effective bulking.

That does not mean an Indian potato shortfall is inevitable. Much of the commercial crop is irrigated, and local outcomes will depend on groundwater access, reservoir availability, planting dates, temperatures and the distribution of any post-monsoon rain.

The present evidence supports describing India as facing an elevated production risk—not a confirmed potato-production loss.

What has changed since 2 September?

The earlier PNT report identified India as one of the first major potato regions where the developing El Niño could leave a measurable legacy in soil moisture and irrigation reserves.

Three developments now reinforce that warning:

WMO has raised confidence in El Niño persisting through February 2027 to nearly 100%;
observed Pacific temperature anomalies have continued to strengthen; and
India has completed August with a 16% monthly rainfall deficit, while September is also expected to receive below-normal rain.

The new information strengthens the warning but does not overturn the careful attribution used in the original report. No authoritative national estimate of Indian potato losses attributable to El Niño has been published.

Nor has evidence emerged of a worldwide potato shortage caused by the event.

The next evidence will come from fields

India will be one of the most important potato regions to watch during October and November as planting accelerates. Emergence, irrigation availability and early-season temperatures will provide the first meaningful indications of whether the weak monsoon is translating into potato-crop stress.

Elsewhere, attention will turn towards the October–December rains in East Africa, the Southern African summer rainfall season, spring conditions in Australia and New Zealand, and winter snow accumulation across the potato-producing northwestern United States and western Canada.

Europe’s current potato losses, meanwhile, remain primarily documented as consequences of regional heat and drought. Direct attribution to El Niño is still uncertain and should not be assumed merely because the events occurred during the development of the Pacific phenomenon.

The central message for the global potato industry is therefore stronger, but still measured: El Niño is intensifying more decisively than previously reported, and the window for preparation is narrowing. The crop consequences, however, must still be established region by region, season by season and field by field.