No El Nino, IMD predicts 105 per cent rainfall this season

It said the monsoon season was likely to bring rainfall that was 105 per cent of the long-period average. The long-period average rainfall for the season is 87 cm. This means that India could receive over 91 cm (105 per cent of 87 cm) of rainfall this season over the entire four-month season.

If it turns out to be so, this would be the fifth time in the last seven years — since 2019 — that the country would receive 100 per cent or more rainfall in the season. It would also be the second consecutive year of ‘above normal’ rainfall, an IMD categorisation that refers to rainfall in excess of 104 per cent of normal. IMD defines 96-104 per cent of rainfall as ‘normal’, between 104 and 110 per cent as ‘above normal’, and anything above that as ‘excess’. Last year, 2024, had produced 108 per cent of normal rainfall.

“All models are showing that the ENSO condition in the Pacific Ocean is expected to remain neutral at least through the end of the monsoon season. The IOD is also neutral. And the winter and spring snow cover over the northern hemisphere including Eurasia is less than normal, which is good from monsoon rainfall point of view. Monsoon rains are inversely related to the extent of snow cover over this region. So, the conditions are all favourable for good rainfall over India in the coming season,” M Ravichandran, secretary in the Ministry of Earth Sciences, said while releasing the forecast.

ENSO and IOD refer to the condition of sea surface temperatures in the Pacific and Indian Oceans respectively. Both of them influence monsoon rainfall. If the sea surface temperature in the eastern Pacific Ocean, off the cost of South America, is warmer than usual, a condition called El Nino, rainfall over India during the monsoon season is generally adversely affected. The opposite condition, called La Nina, favours good rainfall. IOD refers to the difference in temperatures in the Bay of Bengal and Arabian Sea sides of the Indian ocean. IOD is considered positive when the Arabian Sea side is warmer than the Bay of Bengal side. This is generally favourable for Indian monsoon.

Right now, both ENSO and IOD are in neutral condition, so at least neither of them are unfavourable.

IMD’s April forecasts for the monsoon rainfall have been fairly accurate in recent times. The actual rainfall in the previous four years (2021-2024) deviated from the April forecast by 2.27 percentage points, well within the forecast range of four per cent.

Almost 75 per cent of India’s annual rains are realised in the four-month monsoon season. The rainfall received during this time is absolutely critical for irrigation, drinking water, power generation, and economy in general.

The April forecasts are followed by an update in May during which the IMD also shares its predictions for the four broad geographical regions as well as the expected monthly distribution of rainfall during the season. This is the time when it also announces the likely date of onset of monsoon on the Kerala coast, usually June 1, that marks the official beginning of the rainy season.

Information shared by IMD showed that nearly the entire country, except Tamil Nadu, parts of Bihar and Jharkhand, and the northeastern states, were likely to get good rainfall. The central peninsular region, comprising of parts of eastern Maharashtra, southern Madhya Pradesh and Chhattisgarh, Andhra Pradesh and Telangana were possibly in for particularly bountiful rains.

Source: IMD