IMD forecasts ‘below normal’ monsoon for 2026

• The India Meteorological Department (IMD) has forecast below normal Southwest Monsoon rainfall (June to September) this year across the country.

• The forecast based on both dynamical and statistical models suggests that quantitatively, the monsoon seasonal rainfall is likely to be 92 per cent of the Long Period Average (LPA) with a model error of ±5 per cent. 

• The LPA of the seasonal rainfall over the country for the period 1971-2020 is 87 cm.

• LPA of rainfall is the rainfall recorded over a particular region for a given interval (like month or season) average over a long period like 30 years, 50 years, etc. It acts as a benchmark while forecasting the quantitative rainfall for that region for a specific month or season.

• One of the reasons for below normal rainfall could be the emergence of the El Nino conditions.

• El Nino conditions are associated with weaker monsoon winds and drier conditions in India.

• Currently, weak La Nina conditions are transitioning to ENSO-neutral conditions over the equatorial Pacific.

• According to the IMD, climate models indicate that El Nino conditions are likely to emerge around June.

How does the IMD forecast monsoon?

• The India Meteorological Department (IMD) issues operational forecast for the Southwest Monsoon season (June to September) rainfall for the country as a whole in two stages. 

• The first stage forecast is issued in April and the second stage forecast is issued by the end of May.

• Since 2021 IMD has implemented a new strategy for issuing monthly and seasonal operational forecasts for the Southwest Monsoon rainfall over the country by modifying the existing two stage forecasting strategy. 

• The new strategy uses both dynamical and statistical forecasting system. Multi-Model Ensemble (MME) forecasting system based on coupled global climate models (CGCMs) from different global climate prediction centres, including IMD’s Monsoon Mission Climate Forecast System (MMCFS) is used in dynamical forecast system. 

• The MME forecast for the 2026 Southwest Monsoon seasonal rainfall was prepared based on the April initial conditions and using a group of coupled climate models that have highest prediction skill over the Indian monsoon region.

There are 5 categories of monsoon rainfall: 

i) Deficient (less than 90% of LPA)

ii) Below normal (90 to 95% of LPA)

iii) Normal (96 to 104% of LPA)

iii) Above normal (105 to 110% of LPA)

iv) Excess (more than 110% of LPA).

What is El Nino and La Nina?

• El Nino and La Nina events are a natural part of the global climate system. They occur when the Pacific Ocean and the atmosphere above it change from their neutral (‘normal’) state for several seasons.

• El Nino, which is the warming of the waters in the Pacific Ocean near South America, is generally associated with the weakening of monsoon winds and dry weather in India.    

• La Nina, which is the opposite of El Nino, typically brings good rainfall during the monsoon season.

• These changes in the Pacific Ocean and its overlying atmosphere occur in a cycle known as the El Nino-Southern Oscillation (ENSO). 

• The term ‘El Nino’ translates from Spanish as ‘the boy-child’. Peruvian fishermen originally used the term to describe the appearance, around Christmas, of a warm ocean current off the South American coast. It is now the commonly accepted term to describe the warming of the central and eastern tropical Pacific Ocean. 

• ‘La Nina’ translates as ‘girl-child’ and is the opposite ENSO phase to El Nino.

Importance of normal monsoon in India

• Monsoon brings relief to dry and parched land in the form of rain, and affects Indian agriculture in a very substantial measure. The impact of the  monsoon on Indian economy is more pronounced. 

• Normal rain is critical for India’s agricultural landscape, with 52 per cent of the net cultivated area relying on it. 

• It is also crucial for the replenishing of reservoirs critical for drinking water apart from power generation across the country.

• Rain-fed agriculture accounts for about 40 per cent of the country’s total food production, making it a crucial contributor to India’s food security and economic stability. 

• Excessive rain leads to floods in certain areas, while little or no rain in other parts bringing drought and famine resulting in acute distress to millions.