IMD Downgrades 2026 Monsoon Forecast to 90% of Average as El Niño Strengthens

India's monsoon outlook darkened in late May, when the India Meteorological Department cut its forecast for the June–September southwest monsoon to 90% of the Long Period Average — a downgrade from the 92% projected in April, and a figure that carries a 60% probability of an outright deficient season.

The numbers, published in IMD's updated long-range forecast in its late-May release, translate the strengthening El Niño into concrete terms for the country most exposed to its rainfall shadow. The Long Period Average against which the forecast is measured is 868.6 mm, computed over 1971–2020. A season below 90% of that benchmark is classified as deficient — and IMD now rates that outcome more likely than not, at 60%, against a climatological probability of just 16%.

The El Niño arithmetic

IMD named the driver but did not put a number on it. The release records that ENSO conditions are "transitioning towards El Nino conditions over the equatorial Pacific region," and that the department's Monsoon Mission coupled forecast model (MMCFS), along with other climate models, indicates El Niño "likely to develop during the southwest monsoon season." It offers no probability figure for that development and makes no statement about the following winter — readers will find quantified ENSO probabilities in NOAA's monthly diagnostic discussion rather than in IMD's monsoon outlook.

Where IMD does quantify, the number is stark: taken together, the five rainfall categories imply an 84% probability of below-normal-or-less rainfall for the country as a whole.

Compounding the problem, the Indian Ocean offers no rescue this year. IMD expects the Indian Ocean Dipole to remain neutral during the monsoon. In some past El Niño years, a positive IOD — warm water in the western Indian Ocean — has partially offset the Pacific's drying influence over India. With the IOD flat through the season, that compensating support is absent from the forecast. The mechanics of how these ocean patterns tug at the monsoon are laid out in the science of El Niño.

A late start, and an uneven map

The season began on the back foot. Monsoon onset over Kerala came on 4 June 2026, three days later than the climatological norm — not unusual in itself, but consistent with the sluggish setup.

Geographically, the forecast is not uniform. IMD expects below-normal seasonal rainfall over most of the country, with normal to above-normal rainfall likely only over some areas of Northwest and Northeast India, eastern parts of peninsular India and adjoining east-central India, and isolated pockets of East India. The department notes that its model gives no signal at all over some land areas. For the core agricultural belts that fall outside those exceptions, the guidance points the other way.

Why the stakes are high

The southwest monsoon delivers the bulk of India's annual rainfall and irrigates the kharif crop — rice, pulses, oilseeds, cotton — planted through June and July. A season near 90% of LPA does not automatically mean crop failure; distribution across the season and across regions matters as much as the national total. But a 60% chance of deficiency is unusually stark language for IMD's probabilistic forecasts, and it puts reservoir management, sowing decisions and rural incomes on watch through September.

The Indian subcontinent's dry tilt also features in the World Meteorological Organization's global outlook for the August–October season, which places India alongside southern Australia and parts of the Caribbean on the dry side of the El Niño rainfall ledger — part of the broader pattern of global impacts now taking shape.

What comes next

IMD's forecast is a seasonal average, and the department updates its guidance as the season unfolds, with an end-of-season review expected in late September. By then, the question will have shifted from how much rain fell to how the shortfall was distributed — and to what the winter holds, with El Niño forecast to persist at strength into 2027. For India, the 2026 monsoon is shaping up as the clearest early test of how hard this event will bite on land.