What Happened
- Private weather forecasting agency Skymet has predicted a below-normal southwest monsoon for India in 2026, projecting seasonal rainfall at 94% of the Long Period Average (LPA), with a margin of error of ±5%.
- The LPA for the June–September monsoon season is 868.6 mm (based on 1971–2020 data, revised by IMD); rainfall at 94% of LPA places the season in the official "below normal" category (90–96% of LPA).
- The primary driver of the subdued forecast is the possible re-emergence of El Niño conditions later in the monsoon season, expected to strengthen through August–September — historically the most critical months for rainfall accumulation.
- Punjab, Haryana, Rajasthan, and Central India are likely to see the sharpest deficits, while the east and northeast are expected to fare comparatively better.
- Probability distribution from Skymet: 0% chance of excess rainfall, 10% above normal, 20% normal, 40% below normal, 30% drought — indicating a combined 70% probability of deficient conditions.
Static Topic Bridges
Long Period Average (LPA) and IMD's Monsoon Classification System
The Long Period Average (LPA) is the benchmark rainfall figure against which the India Meteorological Department (IMD) measures each monsoon season's performance. It is computed as the average rainfall over a 50-year period across the country (for the June–September season), updated every decade as new data is incorporated. The current LPA is based on 1971–2020 data and stands at 868.6 mm for the all-India southwest monsoon season.
- LPA base period: 1971–2020 (previously 1961–2010: 880.6 mm; revised downward)
- All-India LPA (JJAS): 868.6 mm
- IMD rainfall categories:
- Excess: >110% of LPA
- Above Normal: 104–110% of LPA
- Normal: 96–104% of LPA
- Below Normal: 90–96% of LPA
- Deficient: <90% of LPA
- IMD (government) releases its official forecast in April (long-range) and May/June (updated)
- Skymet is a private agency whose forecast often precedes IMD's official forecast
Connection to this news: Skymet's 94% forecast puts the 2026 monsoon squarely in the "below normal" category by IMD's own classification, though the ±5% error margin means an outcome anywhere from 89% (deficient) to 99% (near-normal) is statistically possible.
Southwest Monsoon — Mechanism and Agricultural Significance
The Southwest Monsoon (June–September) is the primary source of rainfall for approximately 60% of India's net sown area and accounts for ~75% of India's total annual precipitation. It originates in the Indian Ocean and Arabian Sea, driven by the differential heating between the Asian landmass and the ocean — the land heats up faster in summer, creating a low-pressure zone that draws in moisture-laden winds from the sea. The monsoon has two branches: the Arabian Sea branch (hits Kerala first, then moves into the Western Ghats and Central India) and the Bay of Bengal branch (enters through northeast India and spreads westward).
- Normal onset date over Kerala: June 1 (±7 days)
- Withdrawal from northwest Rajasthan: typically September 1, complete withdrawal by October 15
- States most dependent: Bihar, UP, Madhya Pradesh, Rajasthan, Maharashtra (kharif sowing)
- Kharif crops sown during monsoon: rice, maize, cotton, soybean, groundnut, tur (arhar)
- Agriculture's share of GDP: approximately 15–17% (2024-25)
- Approximately 50% of India's agriculture is still rain-fed (not irrigated), making LPA deviations economically significant
- Below-normal monsoon → lower reservoir storage → rabi crop irrigation also affected → food price inflation
Connection to this news: A 94% LPA monsoon in 2026 could reduce kharif crop output, particularly of pulses and oilseeds in rain-dependent regions, feeding into food inflation — directly relevant to the RBI's CPI management challenge.
El Niño — Definition, Mechanism, and India Linkage
El Niño is the warm phase of the El Niño–Southern Oscillation (ENSO) phenomenon, characterised by anomalous warming of sea surface temperatures (SST) in the central and eastern equatorial Pacific Ocean. When the Pacific warms, it disrupts the Walker Circulation — the large-scale atmospheric circulation that normally drives moisture toward Asia — weakening the southwest monsoon over India. Historically, approximately 60% of El Niño years have seen below-normal monsoon rainfall in India, though the relationship is not deterministic.
- ENSO: El Niño (warm phase) / La Niña (cool phase); monitored via Niño 3.4 index
- El Niño threshold: SST anomaly of +0.5°C or more in the Niño 3.4 region for 5+ consecutive overlapping 3-month periods
- India–El Niño correlation: ~60% of El Niño years coincide with below-normal Indian monsoon
- 2023 had a strong El Niño → 2023 southwest monsoon was below normal (94% of LPA)
- Indian Ocean Dipole (IOD): a modulating factor — positive IOD can partially offset El Niño's suppressing effect on Indian monsoon
- ENSO monitoring: NOAA (USA), Australian Bureau of Meteorology, IMD
Connection to this news: Skymet's below-normal 2026 forecast is driven specifically by the anticipated return of El Niño conditions in the second half of the monsoon season (August–September), which are historically the most critical months for rainfall accumulation in northwestern and central India.
Key Facts & Data
- Skymet 2026 monsoon forecast: 94% of LPA (below normal), ±5% error margin
- LPA (all-India JJAS, 1971–2020 base): 868.6 mm
- IMD's "below normal" category: 90–96% of LPA
- Probability of below normal or drought (Skymet): 70% combined
- Expected worst-affected regions: Punjab, Haryana, Rajasthan, Central India
- El Niño expected to intensify from August–September 2026
- Normal monsoon onset date over Kerala: June 1
- Kharif sowing season: June–July (rice, maize, cotton, soybean, groundnut)
- IMD established: 1875; headquartered in New Delhi; under Ministry of Earth Sciences
- Skymet is India's first private weather forecasting company