Monsoon 2026: IMD Forecasts 90% of LPA as Onset Slips Past May 26
IMD's second-stage forecast puts June-September 2026 at 90% of LPA with a 60% chance of deficient rainfall - the first below-average monsoon call in three years, as El Nino nears certainty.
India's 2026 Monsoon Is Late, Weak, and Politically Charged — Here's What the Numbers Say
The southwest monsoon missed its own revised deadline. India's Meteorological Department had revised the onset forecast over Kerala to May 26 — five days ahead of the standard June 1 climatological normal — but as of May 30, 2026, the official declaration has not been made. IMD now expects onset between June 2 and June 4, with a ±4-day model error. The delay comes pinned on a developing typhoon over the western Pacific pulling moisture away from the Arabian Sea, and a cyclonic circulation over Lakshadweep limiting rainfall activity over Kerala's coast.
On May 29, IMD issued its second-stage Long Range Forecast (LRF) at the Ministry of Earth Sciences in New Delhi, delivering a downgrade: the June–September 2026 season will receive 90 per cent of the Long Period Average (LPA), with an estimated model error of ±4 per cent. That figure places this season in the "below normal" band. The 60 per cent probability of a fully deficient season — where rainfall falls below 90 per cent of LPA — is more than double the historical climatological probability of 16 per cent. This is the first below-average forecast in three years, and it matters because two-thirds of India's agricultural land still depends on rain.
What Is IMD Watching Before Declaring Onset
IMD does not declare monsoon onset over Kerala on rainfall alone. Three simultaneous conditions must hold after May 10: at least 60 per cent of 14 designated stations — stretching from Minicoy and Amini in the Lakshadweep group through Thiruvananthapuram, Kochi, Kozhikode, Kannur, and Mangalore — must report 2.5 mm or more of rain on two consecutive days. Wind measurements must show the depth of westerlies maintained up to 600 hPa, with zonal wind speed of the order of 15–20 knots at 925 hPa. Outgoing longwave radiation, a proxy for persistent cloud cover, must also fall below threshold levels.
As of May 25, none of these criteria had been simultaneously met. Parts of Kerala had already received heavy showers, but isolated or convective rain events do not satisfy the sustained-westerly requirement. IMD's Director General of Meteorology, Dr. Mrutyunjay Mohapatra, had earlier flagged that the monsoon's Andaman and Nicobar Islands arrival (which preceded the Kerala onset) occurred on schedule, and atmospheric dynamics in the Arabian Sea would be monitored closely for the next movement.
The onset over Kerala is the ceremonial starting gun for the country's most consequential weather season. It typically takes another six to seven weeks for the monsoon to cover the entire country, reaching Delhi and Rajasthan by late June or early July under normal conditions. A delayed onset over Kerala does not always mean a delayed withdrawal, but in years when onset is weak, the mid-season "break" periods — dry spells lasting weeks — tend to be longer and more damaging to standing crops.
The 90 Per Cent Number: What It Hides
The headline figure of 90 per cent of LPA sounds precise. It is not, and IMD says as much. The ±4 per cent model error means the season could land anywhere between 86 and 94 per cent of LPA. More importantly, the all-India average obscures the spatial distribution that will actually determine whether farmers in Vidarbha, pastoralists in Bundelkhand, or rice growers in Odisha have a workable season.
IMD's updated regional guidance from the second-stage LRF is stark. Below-normal seasonal rainfall is "most likely over most parts of the country," with limited exceptions.
| Region | Seasonal Rainfall Outlook (June–Sep 2026) |
|---|---|
| Northwest India | Likely near-normal to below-normal |
| Northeast India | Most likely near-normal; only region with brighter outlook |
| Central India (Monsoon Core Zone) | Below normal (<94% LPA); most affected |
| South Peninsular India (eastern parts) | Normal to above-normal in some pockets |
| East India (selected pockets) | Normal to above-normal in isolated areas |
| All-India JJAS Average | ~90% of LPA (±4%) |
The "monsoon core zone" designation matters here. This belt — running through central Maharashtra, Madhya Pradesh, Chhattisgarh, Telangana, and parts of Odisha and Jharkhand — accounts for a disproportionate share of India's rain-fed kharif output. Rice, soybean, cotton, tur dal, and coarse cereals are all sown here between June and August. A deficient core-zone season translates directly into lower yields, higher procurement uncertainty, and food price stress in the second half of the year.
June 2026 specifically is forecast at 92 per cent of LPA — slightly less deficient than the full-season number, which implies the forecast models expect a more pronounced drying trend from July onward as El Niño strengthens.
El Niño: The Engine Behind the Downgrade
IMD revised its forecast downward from the April first-stage estimate of 92 per cent to the current 90 per cent primarily because El Niño development has become near-certain. Climate models now show a 92 per cent probability that El Niño conditions will prevail during the June–September period, with the phenomenon expected to intensify through the second half of the season.
El Niño — the periodic warming of central and eastern equatorial Pacific sea-surface temperatures — disrupts the Walker Circulation, weakening the moisture-bearing winds that drive India's monsoon. The relationship is not deterministic: India has had adequate monsoon years during weak El Niño episodes, and the Indian Ocean Dipole (IOD) can partially counterbalance El Niño's suppressive effect. IMD's second-stage forecast notes the IOD is expected to remain "neutral" through the season, removing what could have been a compensating influence.
The 2026 El Niño is being tracked by some modelling centres as a potentially strong event, though IMD has not used the phrase "super El Niño" in official communications. The distinction matters for agricultural planning: a moderate El Niño that weakens core-zone rainfall by 10 per cent is very different from a strong event that pushes the country into a formal drought by IMD's classification criteria (seasonal rainfall at or below 90 per cent of LPA over a meteorological sub-division).
There is also a longer-arc climate context. Research consistently points to a warming Indian Ocean as a modifying factor in how El Niño expresses itself over South Asia. A warmer Indian Ocean tends to strengthen local convection and can, in some configurations, partially offset El Niño's drying signal. Whether this ameliorating effect operates strongly enough in 2026 to prevent a full drought in vulnerable sub-divisions remains the key uncertainty heading into July.
What Farmers and Agriculture Planners Are Facing
India's kharif season begins with pre-monsoon land preparation in May and intensive sowing from June through August. The Agriculture Ministry, aware of the adverse forecast, announced a contingency buffer of 174,000 quintals of seeds above and beyond the 1.73 million tonnes required for normal kharif demand — intended to support resowing if early-planted crops fail due to dry spells or delayed monsoon coverage.
Roughly 60 per cent of India's farming households are largely rain-fed and will have limited ability to fall back on irrigation. Marginal and small farmers — who constitute the majority of the country's 140 million farm holdings — face compounded exposure: rising input costs, inadequate access to crop insurance, and now a forecast that substantially reduces the probability of a full, evenly distributed season.
At the crop level, the risk hierarchy runs roughly as follows. Pulses and oilseeds (tur, urad, groundnut, soybean) require well-distributed mid-season rainfall and are highly sensitive to dry spells in July and August. Cotton, grown heavily in Maharashtra and Gujarat, can survive moderate water stress during vegetative stages but suffers irreversible yield losses during boll formation. Paddy, sown across eastern India, requires more consistent waterlogging; eastern states may be somewhat less exposed given the regional forecasts, but the Monsoon Core Zone rice belt in Chhattisgarh and Jharkhand will need careful watching.
The government's buffer seed strategy, while prudent, addresses only the supply of planting material — it does not address the soil moisture, groundwater, or reservoir-level gaps that a deficient season will create for the second irrigation cycle used for rabi (winter) crops.
Reservoirs Entering the Season Under Pressure
India's 166 Central Water Commission-monitored reservoirs held 63.2 BCM of water as of May 14, 2026 — 34.45 per cent of total live capacity. This represents a decline of approximately 8 BCM in two weeks from April-end levels, typical of the pre-monsoon drawdown. However, Down To Earth's May 2026 monitoring data shows that 13 major reservoirs have dropped below 50 per cent capacity, with the Krishna Basin at a critical 19.31 per cent, the Narmada Basin at 34.96 per cent, and the Godavari Basin at 36.52 per cent.
These basins are not peripheral. The Godavari and Krishna systems irrigate large portions of Telangana, Andhra Pradesh, and Maharashtra. If the monsoon delivers below-normal rainfall across the western Deccan — consistent with the forecast — reservoir replenishment will be incomplete by September, limiting rabi irrigation in the October–March window.
Urban water utilities in Hyderabad, Bengaluru, Pune, and Nagpur draw from reservoir systems that are already under seasonal stress. A weak monsoon that fails to fill Srisailam, Tungabhadra, or Koyna to useful capacity will carry consequences through the following summer. Urban flood risk is a separate but related dimension: a deficient all-India season can still produce intense, localised heavy-rain events in coastal cities, since climate change is increasing rainfall intensity even as total volumes in some regions decline.
What to Watch
- Official onset declaration: IMD's next formal announcement on Kerala onset is expected by June 3. Check mausam.imd.gov.in/responsive/monsooninformation.php for the official bulletin; the onset date, not the forecast date, triggers the agricultural calendar.
- June monthly rainfall actuals: The June 2026 outlook sits at 92 per cent of LPA — more benign than the full season. If June underperforms even this reduced forecast, it will signal a more severe season than the headline 90 per cent number implies.
- El Niño intensity updates: NOAA and IMD both issue monthly ENSO updates. Watch for any upgrade from "moderate" to "strong" El Niño in the June advisory — that shift would likely prompt another IMD forecast downgrade.
- Kharif sowing progress by first week of July: The Agriculture Ministry releases weekly sowing area data; any fall below five-year averages in pulses or oilseeds by July 15 will be an early signal of yield-season stress.
- Core-zone sub-divisional actuals: The all-India LPA number is the least informative metric to follow. Monitor Vidarbha, Marathwada, and Telangana sub-divisional rainfall data on mausam.imd.gov.in/responsive/rainfallinformation.php — these will be the canary for a drought declaration.
- IOD development: If the Indian Ocean Dipole shifts from neutral to positive by July, it could partially offset El Niño's suppression effect and rescue parts of peninsular India. A negative IOD would worsen the outlook.
- Reservoir fill rate by August 1: CWC publishes weekly bulletin data; 60 per cent or above live storage by August 1 would signal an adequate season for rabi irrigation planning. Below 50 per cent would raise food and water alarms for the following year.
