India may receive above normal or greater rainfall during the south west monsoon season (June-September) in 2025, though some long-term drying trends such as in Northeast India may still hold, according to the Long Range Forecast (LRF) issued by the India Meteorological Department (IMD) on April 15, 2025.
The reasons for this excessive rainfall could be varied such as less than normal snow cover over Eurasia and in the Northern Hemisphere in general and the possible lack of development of an El Niño phenomenon in the equatorial Pacific Ocean or a negative Indian Ocean Dipole (IOD) in the Indian Ocean region, both of which are generally associated with lower rainfall during the south west monsoon season.
The IMD estimates that on an average, the south west monsoon season would likely yield 105 per cent of the long period average (LPA) rainfall for India from June to September 2025. This figure has a model error of +/- 5 percent and the LPA of monsoon seasonal rainfall over the country for the period 1971-2020 is 87 cm, according to the IMD.
The forecast probability of above normal rainfall (105 to 110 per cent of LPA) during the season is 33 per cent with a climatological probability of 16 per cent, as per the IMD. While forecast probability takes into account current weather characteristics of the atmosphere and oceans to predict future occurrences, climatological probability takes into account long term historical rainfall data and averages.
The forecast probability of excess rainfall (greater than 110 per cent of LPA) over India is 26 per cent. Therefore, there is a 59 per cent (33+26) chance of the south west monsoon of 2025 being above normal or excess (greater than 104 percent of LPA).
The distribution of rainfall over the country during the south west monsoon season would be clearer in the next forecast issued by IMD on May 15 but the initial indications are not encouraging for the Northeast, which has been undergoing a long-term drying trend.
“Rainfall in India happens in a dipole pattern as the highest rainfall happens in Northeastern parts and the lowest rainfall occurs in the Thar desert region of Rajasthan. But this pattern has been reversing for the last decade or so,” said M Ravichandran, secretary, Ministry of Earth Sciences, at IMD’s LRF press conference on April 15.
This means that while the desert has been greening because of excess rainfall, the rainforests of the Northeastern regions like Meghalaya have received less rainfall leading to drying. The major underlying reason could be global warming and consequent climate change. The other two regions in the country which may have lower than average rainfall are Ladakh, Tamil Nadu and some parts of Bihar.
The regions which have the highest chances of receiving much higher-than-average rainfall are southern Chattisgarh, northern Andhra Pradesh, Telangana, parts of Maharashtra and southern Odisha.
Large scale global atmospheric and oceanic patterns that impact monsoon rainfall such as the El Niño Southern Oscillation (ENSO) phenomenon in the equatorial Pacific Ocean are in favour of good rainfall during the monsoon season in 2025.
Currently, neutral ENSO conditions (neither El Niño nor La Niña) are prevalent in the equatorial Pacific Ocean and the atmospheric characteristics are similar to a La Niña, according to IMD. During La Niña, cooler than normal sea surface temperatures are observed in the eastern and central equatorial Pacific Ocean which enhances the formation of low-pressure areas in the Bay of Bengal.
This formation of low-pressure areas brings more rainfall to the country in general, especially the central regions. The IMD predicts that neutral ENSO conditions are likely to continue during the monsoon season.
Similarly, neutral IOD conditions are prevalent in the region which are neither good or bad for monsoon rains. A negative IOD could lead to decrease in monsoon rainfall.
The most significant factor that could lead to the predicted increase in rainfall is the reduced snow cover in the northern hemisphere, especially in the Eurasian region, which has an inverse relationship with monsoon rainfall. The snow cover over these regions in the past three months (January-March 2025) has been lower than normal, according to IMD.
This happens because of the ice albedo feedback in which more snow cover reflects back sunlight, and a lack of snow cover leads to absorption of the heat which in turn leads to strong monsoon circulation.