PIB TrackerIMD forecasts below-normal monsoon as El Nino looms
The India Meteorological Department's second-stage long-range forecast for the 2026 southwest monsoon.
What happened
- The India Meteorological Department (IMD) issued its second-stage (updated) Long Range Forecast for the 2026 southwest monsoon season (June–September), along with a separate outlook for June 2026.
- For the country as a whole, seasonal rainfall is now likely to be 90% of the Long Period Average (LPA), with a model error of ±4% — placing the season in the "below normal" category.
- The forecast assigns an 84% probability of below-normal or less rainfall, including a 60% probability of deficient rainfall (defined as less than 90% of LPA).
- Neutral El Niño–Southern Oscillation (ENSO) conditions over the equatorial Pacific are transitioning towards El Niño, which is likely to develop during the monsoon season; neutral Indian Ocean Dipole (IOD) conditions are expected to continue.
- Below-normal rainfall is most likely over most of the country, except parts of Northwest and Northeast India, eastern peninsular India and adjoining east-central India.
- For June 2026 alone, rainfall is likely to be below normal (under 92% of LPA; the June LPA is 165.4 cm), with above-normal heatwave days expected over several states.
Background & context
The southwest monsoon — the four-month rain-bearing system that arrives over Kerala around the first week of June and withdraws by late September — delivers roughly three-quarters of India's annual rainfall and underwrites the entire Kharif cropping season. Because so much of Indian agriculture remains rain-fed and because reservoir storage, hydropower and rural demand all track the rains, the IMD's seasonal outlook is one of the most consequential scientific statements the government issues each year.
IMD operates a two-stage long-range forecasting cycle. The first-stage forecast is released in April, ahead of the season; the second-stage (updated) forecast — the one issued here — is released in late May, just before onset, and revises the April call using fresher ocean–atmosphere data. Since 2021, IMD has based these seasonal forecasts on a Multi-Model Ensemble (MME) system rather than the older statistical-only approach. The MME draws on simulations from several coupled global climate models (CGCMs), including IMD's own Monsoon Mission Climate Forecasting System (MMCFS) model — a dynamical model developed under the Monsoon Mission programme of the Ministry of Earth Sciences. The shift to a dynamical ensemble was intended to improve skill in capturing the physical drivers of the monsoon rather than relying purely on historical correlations.
Two large-scale ocean signals dominate the IMD's reasoning each year. The first is ENSO, the see-saw of sea-surface temperatures and pressure across the equatorial Pacific: its warm phase, El Niño, is broadly associated with weaker Indian monsoons, while its cool phase, La Niña, tends to favour good rains, and a "neutral" phase sits in between. The second is the Indian Ocean Dipole (IOD), the difference in sea-surface temperature between the western and eastern tropical Indian Ocean: a positive IOD generally aids monsoon rainfall, while a neutral or negative IOD removes that support. This year IMD reads ENSO as drifting from neutral towards El Niño during the season, with IOD staying neutral — a combination that withdraws the usual oceanic boost and tilts the balance towards a drier season.
It is worth separating the two halves of any IMD seasonal forecast, because objective questions probe both. The first half is the quantitative outlook — a single percentage of LPA with a stated model error — which tells you the expected all-India seasonal total. The second half is the probabilistic outlook, which spreads the chance of the season across IMD's five rainfall categories; this is why the release can quote a point estimate of 90% of LPA and separate probabilities of 84% (below normal or less) and 60% (deficient). The two are consistent rather than contradictory: the point estimate is the most likely single value, while the probabilities describe how the forecast distribution leans across the category bins. IMD also forecasts the monsoon at finer scales through the season — monthly outlooks (such as the June outlook issued alongside this release) and the homogeneous-region break-up over the four geographical regions — so that planners can read not just the all-India number but where and when the deficit is likely to bite.
For Prelims
- Issuing body: India Meteorological Department (IMD), under the Ministry of Earth Sciences. IMD is India's national meteorological service and the principal agency for weather forecasting, founded in 1875, with its headquarters in New Delhi.
- Forecast type: second-stage / updated Long Range Forecast (LRF) for the southwest monsoon — released in late May, updating the April first-stage forecast.
- Headline number: 2026 seasonal (June–Sep) rainfall likely 90% of LPA, ±4% model error → the below-normal category.
- Probabilities: 84% chance of below-normal-or-less rainfall; 60% chance of deficient rainfall (<90% of LPA).
- LPA value: the Long Period Average of seasonal rainfall, computed over the 1971–2020 period, is 87 cm. (The June LPA alone is 165.4 cm of the monthly figure cited by IMD.)
- Forecast engine: Multi-Model Ensemble (MME), in use since 2021, combining coupled global climate models including IMD's MMCFS (Monsoon Mission Climate Forecasting System) dynamical model.
- Ocean drivers: ENSO transitioning neutral → El Niño during the season; IOD expected to remain neutral.
- Spatial pattern: below-normal rains over most of India, except parts of Northwest & Northeast India, eastern peninsular India and adjoining east-central India; above-normal heatwave days over UP, Haryana, Punjab, Bihar, Odisha, Chhattisgarh, Gujarat and Andhra Pradesh, and below-normal heatwave days over Rajasthan and Jharkhand.
IMD's rainfall categories (the full set — this is the "match the pairs" trap): the seasonal forecast is binned against LPA into five standard classes — Deficient (less than 90% of LPA), Below Normal (90–95%), Normal (96–104%), Above Normal (105–110%) and Excess (more than 110%). The 2026 figure of 90% sits at the boundary of below-normal and deficient, which is why the release pairs the "below normal" headline with a high probability of deficient rainfall.
What this is NOT: "90% of LPA" does not mean rainfall will fall by 90% — it means the season is expected to receive 90% of its long-term average, i.e. about a tenth below normal. The LPA is not a fixed historical constant either; IMD periodically updates the baseline period (now 1971–2020), so the same percentage maps to a slightly different absolute figure than in earlier years. El Niño is not a guarantee of drought — it loads the dice towards weaker rains but does not determine any single season, and a positive IOD or favourable intra-seasonal activity can offset it. The MME is not a purely statistical model; since 2021 it is built on dynamical coupled climate models, distinguishing the current method from IMD's older statistical regression forecasts. And ENSO and IOD are two different oceanic phenomena — ENSO is a Pacific signal, the IOD is an Indian Ocean signal — frequently confused in objective questions.
The wider monsoon-forecasting set (for "how many of these" questions): the southwest (summer) monsoon, June–September, is one of two monsoon systems IMD forecasts; the other is the northeast (winter) monsoon, October–December, which is decisive for Tamil Nadu and the southeastern peninsula. The all-India seasonal LRF is built up from forecasts for four broad homogeneous regions — Northwest India, Central India, South Peninsula and Northeast India — and IMD separately issues the onset date over Kerala, the date that conventionally marks the start of the season. Alongside the seasonal call, IMD runs short-range and medium-range weather forecasting and a colour-coded warning system (green, yellow, orange, red) for extreme events. Distinguishing the seasonal long-range forecast from the daily/medium-range weather forecast is a common point of confusion: the LRF is a probabilistic, season-scale statement, not a day-by-day rain prediction.
Why it matters
A below-normal monsoon with a 60% probability of outright deficiency is a planning signal across several sectors at once. For agriculture, the Kharif sowing window opens with onset; a weak and uneven monsoon raises the risk for rain-fed crops such as pulses, oilseeds, coarse cereals and cotton, and pushes a premium on short-duration and drought-tolerant varieties and on assured irrigation. For water and power, below-normal rains stress reservoir storage that feeds both irrigation and hydropower into the post-monsoon months. For prices and the macro-economy, a deficient monsoon can lift food inflation and rural distress, with knock-on effects for monetary policy and rural demand. The simultaneous warning of above-normal heatwave days over a swathe of the Indo-Gangetic plain and eastern India compounds the stress, linking the forecast directly to disaster-management preparedness, public-health heat-action plans and electricity peak demand. A credible seasonal forecast lets the agriculture ministry, states and water managers pre-position seed reserves, contingency cropping plans and relief machinery before the season turns — which is precisely the value of moving from statistical to dynamical ensemble forecasting.