The southwest monsoon rains are expected to hit India’s southern coast on May 27, five days earlier than usual, marking the earliest arrival in at least five years, raising hopes for bumper harvests of crops such as rice, corn, onion, cotton, bajra (pearl millet), maize, tur, black gram and soybean.
The monsoon, the lifeblood of the country’s $4 trillion economy, delivers nearly 70 per cent of the rain that India needs to water farms and recharge aquifers and reservoirs.
Nearly half of India’s farmland, without any irrigation cover, depends on the annual June-September rains to grow a number of crops. The arrival of the main rain-bearing system over the Indian mainland is officially declared when it reaches Kerala, usually around June 1.
The monsoon typically covers the entire country by July 8. It starts withdrawing from northwest India around September 17 and completes by October 15. The monsoon had set in over the southern state on May 30 last year; June 8 in 2023; May 29 in 2022; June 3 in 2021; June 1 in 2020; June 8 in 2019; and May 29 in 2018.
An IMD official said there is no direct relationship between the onset date and the total rainfall over the country during the season.”The monsoon arriving early or late in Kerala does not mean it will cover other parts of the country accordingly. It is characterised by large-scale variabilities and global, regional and local features,” the official said.
According to IMD, analysing circulation anomalies at the sub-seasonal scale, outputs from NWP-based models indicate the influence of moist equatorial waves like equatorial Rossby waves. These waves, which could either be progressing or quasi-stationary, are expected to begin impacting weather patterns over the Indian region in the coming days. Their presence may accelerate the advance of the monsoon.
The forecast indicates that regions such as Jammu and Kashmir, Ladakh, Tamil Nadu, Bihar and the north-eastern states might experience below-normal rainfall. In contrast, states forming the core monsoon zone, including Madhya Pradesh, Rajasthan, Maharashtra, Odisha, Chhattisgarh, Uttar Pradesh, and West Bengal, are expected to receive normal to above-normal rainfall. This distribution is crucial as the core monsoon zone is primarily dependent on rain-fed agriculture, making the forecast critical for farmers in these areas.
The IMD had, in April, forecast above-normal cumulative rainfall in the 2025 monsoon season, ruling out the possibility of El Niño conditions, which are associated with below-normal rainfall in the Indian subcontinent.
“India is likely to see above-normal rainfall in the four-month monsoon season (June to September), with cumulative rainfall estimated at 105 per cent (with a model error of 5 per cent) of the long-period average of 87 cm,” M Ravichandran, secretary in the Ministry of Earth Sciences, had said.
According to the IMD, rainfall between 96 per cent and 104 per cent of the 50-year average of 87 cm is considered ‘normal’.
Rainfall less than 90 per cent of the long-period average is considered ‘deficient’; between 90 per cent and 95 per cent is ‘below normal’; between 105 per cent and 110 per cent is ‘above normal’; and more than 110 per cent is considered ‘excess’ precipitation.
The monsoon is crucial for India’s agriculture sector, which supports the livelihood of about 42.3 per cent of the population and contributes 18.2 per cent to the country’s GDP.
It is also vital for replenishing reservoirs critical for drinking water and power generation across the country.
