- Why in news
- On 29 May 2026 the IMD issued its updated second-stage forecast for the 2026 southwest monsoon. It expects seasonal rainfall at 90% of the Long Period Average, with an El Nino likely to develop, and also gave a June rainfall, temperature and heatwave outlook.
- What it is
- The IMD issues two-stage long range forecasts for the southwest monsoon (June-September), the first in April and the update at the end of May. Since 2021 it has used a Multi-Model Ensemble system that combines coupled global climate models, including IMD's own Monsoon Mission Climate Forecasting System (MMCFS). Forecasts are given as a percentage of the Long Period Average (LPA) and as probabilities for rainfall categories.
- Forecast value
- Seasonal rainfall for India is forecast at 90% of the LPA, with a model error of plus or minus 4%.
- LPA base
- The LPA of seasonal rainfall is 87 cm, based on 1971-2020 data.
- Forecast system
- IMD uses a Multi-Model Ensemble built from coupled global climate models, including its own MMCFS, for monthly and seasonal forecasts.
- ENSO and IOD
- ENSO is moving from neutral towards El Nino, while the Indian Ocean Dipole is expected to stay neutral through the monsoon.
- Regions covered
- Forecasts cover four homogeneous regions (northwest, central, south Peninsula, northeast India) and the Monsoon Core Zone of rainfed agriculture areas.
- Forecast
- Seasonal rainfall is forecast at 92% of LPA, with a model error of ±5%. This falls in the below-normal band.
- Ocean signals
- MMCFS suggests El Niño conditions may develop during the monsoon season. Positive IOD is likely towards the end of the season.
- Snow cover link
- Northern Hemisphere winter and spring snow cover has a general inverse relationship with monsoon rainfall.
Don’t confuse with ENSO vs IOD: ENSO is the Pacific ocean-atmosphere cycle (El Nino and La Nina). The IOD is the sea surface temperature difference across the Indian Ocean. Both affect the monsoon.
Don’t confuse with Extended range vs long range forecast: Long range forecasts cover a month or a season. Extended range forecasts are weekly averages for the next four weeks. Short to medium range forecasts are issued daily.
Don’t confuse with Seasonal vs monthly forecast: The seasonal forecast covers June-September for the whole country. Monthly forecasts are issued at the end of June, July and August for the next month.
Science and technology: 57 Prelims questions since 2013; most test the concept behind the news, not the news itself. In Mains, 12 news-triggered questions.
Why it matters
- Early forecasts help farmers, water managers and power planners prepare for a deficit year.
- Heatwave and temperature outlooks let states ready cooling shelters, water supply and health systems.
- Early guidance helps agriculture, water management and power planning.
- Rainfall below normal can affect kharif output, food inflation and rural incomes.
Problems
- Forecast error remains, and regional and local rainfall is hard to predict.
- A below-normal monsoon strains rainfed agriculture, reservoirs, hydropower and drinking water.
- Model error of ±5% and weak signals in some regions limit accuracy.
- Seasonal averages hide uneven spatial and temporal rainfall distribution.
Way forward
- Use contingency crop plans, water conservation and drought monitoring tied to IMD early warnings.
- Use impact-based forecasts to prepare state and district responses.
- Improve regional and sub-seasonal forecasts, and communicate them to farmers in local languages.
- Prepare contingency crop plans and water-saving measures in advance.
Put in your answer
Preparedness advice: States and districts are advised to keep cooling shelters, safe drinking water and health surveillance ready for heatwaves.
El Niño and monsoon: El Niño development during the season is a known risk factor for weaker monsoon rainfall. MMCFS points to its possible development.
- 2015Mains GS1 · Q18Whether Indian monsoon behaviour changing due to humanised landscapes
- 2014Mains GS3 · Q14Preparedness for likely El Nino and La Nina drought fallouts
- 2022Mains GS1 · Q5Meaning of IMD's colour-coded weather warnings for cyclone-prone areas
- 2017Prelims Q66IOD definition and its role in El Nino monsoon impact
- 2020Prelims Q93Statements on OMT depth and monsoon rainfall forecasting use
- 2011Prelims Q52La Nina versus El Nino: temperature differences and monsoon effects
- 2026Prelims Q84Which statements on the Bharat Forecast System weather model are correct?
UPSC’s own questions that come close to this issue, from our Prelims and Mains banks.
No practice question for this one; the card may still help an answer. Why: Lasting topic on forecasting method (Multi-Model Ensemble, Monsoon Mission), but seasonal numbers are routine and hard to frame as statements.
Worth revising until Prelims 2027: most news questions come within two years of the event.