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VIDEO EXPLAINER | 2 NOVEMBER 2026
On 29 May 2026 the India Meteorological Department cut its 2026 south-west monsoon forecast to 90% of the Long Period Average (87 cm, the 1971-2020 mean), down from 92% in April, and put the chance of below-normal or deficient rain at 84%, citing developing El Nino conditions. The monsoon reached Kerala on 4 June, three days late. The next day the RBI’s Monetary Policy Committee held the repo rate at 5.25% and flagged the sub-normal monsoon forecast and El Nino as a risk to food inflation. IMD declared El Nino on 12 June, and June closed with a deficit of about 40%.
What happened
IMD issued its first-stage forecast for the 2026 monsoon on 13 April 2026.
The April 2026 first-stage forecast put seasonal rainfall at 92% of the LPA (below normal).
On 29 May 2026 IMD issued its second-stage (updated) long-range forecast: south-west monsoon (June-September) rainfall likely to be 90% of the LPA, with a model error of plus or minus 4%.
IMD’s 29 May forecast gave an 84% probability of below-normal-or-less seasonal rainfall for India as a whole.
IMD gave a 60% probability that 2026 seasonal rainfall would fall in the ‘deficient’ category (below 90% of LPA), against a climatological probability of 16%.
At the 29 May forecast, neutral ENSO conditions were moving towards El Nino, which models expected to develop during the monsoon season.
IMD expected neutral Indian Ocean Dipole (IOD) conditions to continue through the 2026 monsoon season.
IMD forecast below-normal June 2026 rainfall (under 92% of the June LPA) and above-normal heatwave days over many parts of UP, Haryana, Punjab, Bihar, Odisha, Chhattisgarh, Gujarat and Andhra Pradesh.
IMD announced the monsoon’s onset over Kerala on 4 June 2026, three days after the normal date of 1 June (which carries a margin of 7 days).
On 5 June 2026 the RBI’s Monetary Policy Committee unanimously kept the repo rate at 5.25% with a neutral stance.
RBI Governor Sanjay Malhotra said the food outlook was uncertain because of the sub-normal south-west monsoon forecast and El Nino.
IMD declared on Friday 12 June 2026 that El Nino had developed in the Pacific and would strengthen during the monsoon season.
June 2026 ended with a nationwide rainfall shortfall of roughly 40%, with central, eastern and north-eastern states worst hit; Central India’s June deficit was 50.4%.
Background and the rules behind it
The LPA of India’s June-September monsoon rainfall is 87 cm, based on 1971-2020 data.
IMD’s five rainfall categories (% of LPA): deficient under 90; below normal 90-95; normal 96-104; above normal 105-110; excess over 110.
The Madden-Julian Oscillation (MJO) is an eastward-moving pulse of clouds and rain that circles the tropics about every 30-60 days and is tracked in eight phases.
Key terms
- Long Period Average (LPA): Average June-September rainfall over 1971-2020 (87 cm), the benchmark for ‘normal’.
- El Nino: Warm phase of ENSO: an unusually warm central-eastern Pacific, usually weakening India’s monsoon.
- Indian Ocean Dipole (IOD): Temperature difference between the western and eastern Indian Ocean; positive phase usually aids the monsoon.
- Madden-Julian Oscillation (MJO): Eastward-travelling tropical pulse of clouds and rain, recurring every 30-60 days.
- Monsoon Core Zone: Central belt holding most of India’s rain-fed farmland; used in IMD forecasts.
- Repo rate: Rate at which the RBI lends short-term money to banks; its main policy rate.
Constitutional / Legal / Institutional framework
- India Meteorological Department (IMD): Set up in 1875; works under the Ministry of Earth Sciences and issues the official monsoon forecasts.
- Rainfall categories: IMD classifies seasonal rainfall as a percentage of the LPA: deficient below 90, below normal 90-95, normal 96-104.
CLAT angle
- Numbers: LPA 87 cm (1971-2020); 2026 forecast 90% (May) after 92% (April); categories – normal 96-104%, deficient below 90%.
- Cause-effect passage: El Nino suppresses, positive IOD can offset (1997 example), MJO pulses modulate rainfall within the season.
- Economy link: RBI held repo at 5.25% (5 June 2026) and flagged monsoon and El Nino risks to food inflation.
- SW vs NE monsoon: Kerala onset normal 1 June; Tamil Nadu gets about 48% of its annual rain from the NE monsoon.
- Institution: IMD – est. 1875, Ministry of Earth Sciences, Mission Mausam (2025).
Key facts
| Fact | Detail |
|---|---|
| 1875 | IMD established |
| 1997 | Positive IOD offsets El Nino’s monsoon impact |
| 2025-01-14 | IMD’s 150th Foundation Day; Mission Mausam launched |
| 2026-04-13 | IMD first-stage forecast: 92% of LPA |
| 2026-05-29 | IMD second-stage forecast: 90% of LPA |
| 2026-06-04 | Monsoon onset over Kerala |
| 2026-06-05 | RBI MPC holds repo at 5.25%, flags monsoon and El Nino |
| 2026-06-12 | IMD declares El Nino |
Mnemonic / memory hook
Remember the trap.
The LPA is 87 cm (870 mm), not 89 cm (the older 1961-2010 figure). IOD was NEUTRAL in 2026 per IMD – do not say a negative IOD caused the deficit. Normal onset over Kerala is 1 June (+/- 7 days); 2026 onset was 4 June. The RBI statement came on 5 June, after the IMD forecast of 29 May.
Sources
Primary documents and reporting listed in the fact base: pib.gov.in, indianexpress.com, thehindu.com. Lead image: Photo: Rajarshi MITRA from Mumbai, India, CC BY 2.0, via Wikimedia Commons.
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