What Happened
- The APEC Climate Centre (APCC), the apex climate prediction body for the Asia-Pacific region, has issued an El Nino watch, warning that drought-bearing El Nino conditions are likely to emerge by July 2026
- Above-normal temperatures are predicted across India over the next six months, with below-normal rainfall expected during the monsoon season
- The current La Nina phase is transitioning to ENSO-neutral in early 2026, with most climate models predicting El Nino development in the second half of the year
- The El Nino is expected to strengthen during the middle of the Indian monsoon season (July-September) and peak during the Northern Hemisphere winter, raising concerns about drought conditions and agricultural output
Static Topic Bridges
El Nino-Southern Oscillation (ENSO) — Mechanism and Phases
ENSO is a coupled ocean-atmosphere climate phenomenon in the tropical Pacific Ocean that has global impacts on weather patterns. It consists of two opposing phases — El Nino (warm phase) and La Nina (cool phase) — and a neutral phase. El Nino occurs when sea surface temperatures (SSTs) in the central and eastern equatorial Pacific Ocean become anomalously warm (above +0.5 degrees Celsius), weakening the trade winds and disrupting the Walker Circulation.
- El Nino: Warming of SSTs in Nino 3.4 region (5N-5S, 170W-120W) by more than +0.5 degrees Celsius for five consecutive overlapping 3-month periods; weakens Walker Circulation; reduces upwelling off Peru/Ecuador coast
- La Nina: Cooling of SSTs by more than -0.5 degrees Celsius; strengthens trade winds and Walker Circulation; typically enhances Indian monsoon rainfall
- ENSO-Neutral: SST anomalies between -0.5 and +0.5 degrees Celsius
- Walker Circulation: Large-scale atmospheric circulation in the tropics — normally ascending limb over the western Pacific (warm pool) and descending limb over the eastern Pacific; El Nino reverses or weakens this
- Southern Oscillation Index (SOI): Measures atmospheric pressure difference between Tahiti and Darwin; negative SOI indicates El Nino conditions
- Periodicity: ENSO cycles every 2-7 years; not perfectly periodic
- Monitoring bodies: NOAA Climate Prediction Center (US), Bureau of Meteorology (Australia), APCC (Asia-Pacific), IMD and IITM (India)
Connection to this news: The APCC's El Nino watch signals a transition from ENSO-neutral to El Nino phase during the critical monsoon months, which would weaken the Walker Circulation and suppress convective activity over the Indian subcontinent.
El Nino and Indian Summer Monsoon — Historical Relationship
The Indian Summer Monsoon (ISM), active from June to September, provides approximately 70-75% of India's annual rainfall and is critical for kharif agriculture. El Nino events have historically been associated with below-normal monsoon rainfall in India. The mechanism involves El Nino-induced subsidence (sinking air) over the Indian region, which weakens the monsoon circulation.
- Of the 15 major droughts in India between 1950 and 2023, over 60% coincided with El Nino years
- Notable El Nino drought years: 1965, 1972, 1982, 1987, 2002, 2009, 2015 (though 2015 was partially offset by positive IOD)
- Not all El Nino years produce droughts — the relationship is probabilistic, not deterministic (e.g., 1997 had strong El Nino but near-normal monsoon)
- Indian Meteorological Department (IMD) defines "normal" monsoon as rainfall within the range of 96-104% of the Long Period Average (LPA = 87 cm, 1971-2020 baseline)
- Monsoon deficit: Below 90% of LPA is classified as a "drought year" by IMD
- India's kharif crops (rice, pulses, cotton, sugarcane) are directly dependent on monsoon rainfall — a deficit monsoon impacts food production, inflation, and rural employment
Connection to this news: If El Nino materialises by July 2026 as APCC predicts, it would coincide with the peak monsoon months (July-August), potentially suppressing rainfall during the most critical period for kharif sowing and crop development.
Indian Ocean Dipole (IOD) — The Counterbalancing Factor
The Indian Ocean Dipole is an independent ocean-atmosphere phenomenon characterised by the difference in sea surface temperatures between the western and eastern Indian Ocean. A positive IOD (warmer western Indian Ocean, cooler eastern Indian Ocean) can partially or fully counteract the negative impact of El Nino on the Indian monsoon by enhancing moisture supply and convective activity over the Indian subcontinent.
- Positive IOD: SST warmer in western Indian Ocean (near East Africa/Arabian Sea) and cooler in eastern Indian Ocean (near Indonesia/Sumatra); enhances Indian monsoon rainfall
- Negative IOD: Opposite pattern; can exacerbate the drought impact of El Nino
- IOD index = SST anomaly in western equatorial Indian Ocean minus SST anomaly in eastern equatorial Indian Ocean
- IOD and ENSO interaction: El Nino can trigger a positive IOD (anomalous winds near Indonesia bring cold water to the eastern Indian Ocean surface), but the relationship is not always coupled
- 2019 case study: Strong El Nino Modoki + strongest positive IOD on record resulted in above-normal monsoon rainfall in India — demonstrating that IOD can override El Nino's suppressive effect
- 2015 case study: Strong El Nino but positive IOD limited the deficit to moderate levels
- Indian Institute of Tropical Meteorology (IITM), Pune, monitors both ENSO and IOD for monsoon forecasting
- IMD's operational monsoon forecast model considers both ENSO and IOD as key predictors
Connection to this news: Whether the 2026 monsoon will be severely impacted depends not only on El Nino's intensity but also on the IOD phase — a concurrent positive IOD could partially offset El Nino's negative impact, while a negative or neutral IOD would amplify drought risk.
India Meteorological Department (IMD) — Monsoon Forecasting Framework
IMD is India's principal weather forecasting agency, established in 1875 and currently functioning under the Ministry of Earth Sciences. IMD issues two-stage operational monsoon forecasts: the first in April (long-range forecast using statistical and dynamical models) and the second in June (updated forecast). These forecasts are critical for agricultural planning, water resource management, and economic policy.
- IMD's monsoon forecast categories: Above Normal (>104% LPA), Normal (96-104% LPA), Below Normal (90-96% LPA), Deficient (<90% LPA)
- Long Period Average (LPA): 87 cm (1971-2020 baseline); used as the benchmark
- IMD uses the Multi-Model Ensemble (MME) approach combining statistical models with dynamical models (CFSv2, GFS, ECMWF)
- IITM Pune: Develops Monsoon Mission Coupled Forecast System; provides dynamical seasonal prediction
- Monsoon onset: Typically arrives at Kerala coast by 1 June (+/- 7 days); covers entire India by 15 July
- Agricultural impact: India's net sown area is ~140 million hectares; approximately 52% is rain-fed (not irrigated), making these areas highly monsoon-dependent
Connection to this news: IMD's first operational monsoon forecast (due April 2026) will be the first authoritative assessment of whether El Nino's impact on the 2026 monsoon will be significant enough to warrant drought preparedness measures.
Key Facts & Data
- APCC El Nino watch: El Nino conditions likely to emerge by July 2026
- Current ENSO phase: La Nina transitioning to ENSO-neutral in early 2026
- El Nino threshold: SST anomaly above +0.5 degrees Celsius in Nino 3.4 region for 5 overlapping 3-month periods
- Indian monsoon contributes: 70-75% of India's annual rainfall (June-September)
- LPA (Long Period Average): 87 cm (1971-2020 baseline)
- Normal monsoon range: 96-104% of LPA; drought threshold: below 90% of LPA
- Over 60% of major Indian droughts (1950-2023) coincided with El Nino years
- Rain-fed agriculture: ~52% of India's net sown area (~140 million hectares total)
- IMD first monsoon forecast: Expected April 2026
- IOD: Can counterbalance El Nino's negative impact on Indian monsoon (e.g., 2019 — positive IOD + El Nino Modoki = above-normal rainfall)