Satellite image showing cloud cover over India as the southwest monsoon continues. (IMD Photo)A potentially historic El Niño is developing in the Pacific, with a 69 per cent chance of the event becoming stronger than any recorded since 1950, according to the US-based National Oceanic and Atmospheric Administration (NOAA). The phenomenon is expected to strengthen through the end of the year and peak during the Northern Hemisphere winter.For India, however, the biggest impact may come after this year’s southwest monsoon has largely ended. El Niño’s effects on the Indian Ocean and regions around India typically emerge with a lag of several weeks, while the India Meteorological Department (IMD) has said the current monsoon has so far not been affected by the phenomenon.In its monthly El Niño-Southern Oscillation (ENSO) bulletin, NOAA said there is a 90 per cent chance of a “strong” El Niño during the Northern Hemisphere winter. “During the October-December 2026 season, there is a 69 per cent chance of a historic event that would exceed the strength of previous El Niño events dating back to 1950,” it said.Also Read | How an IMD discovery in 1920s changed monsoon forecastsThe agency said the current El Niño strengthened during July and is expected to intensify further in the coming months. “With an event of this magnitude, the chances of experiencing impacts consistent with El Niño are larger,” NOAA said.El Niño is the warm phase of ENSO, a naturally occurring climate pattern driven by changes in sea-surface temperatures and atmospheric conditions across the tropical Pacific. It can alter weather patterns around the world and is associated with a higher likelihood of drought, extreme heat, and below-normal rainfall in some regions.El Niño effects on IndiaFor India, El Niño is significant because years in which the phenomenon occurs have historically been associated with below-average southwest monsoon rainfall. However, there is no one-to-one relationship between the two, and the Indian monsoon is influenced by several other ocean and atmospheric factors.The current monsoon has already recorded below-normal rainfall. India received 491.8 mm of rain between June 1 and August 13, 12 per cent below normal. June recorded a 35.4 per cent deficit, while rainfall in July was close to normal. IMD has forecast below-normal rainfall for August and the remainder of the monsoon season.Story continues below this adAlso Read | Despite recent monsoon revival, why El Niño fears are not over yetThe timing of the developing El Niño could, however, limit its influence on the current monsoon. Its effects are typically reflected over the Indian Ocean and regions closer to India after a lag of around 40-45 days. By the time those effects become more pronounced, the southwest monsoon will be close to its official withdrawal date of September 30.Another factor that could partly offset El Niño’s influence is the Indian Ocean Dipole (IOD), the Indian Ocean counterpart of ENSO. The IOD is currently neutral, but IMD expects it to turn positive towards the end of the monsoon season. A positive IOD can counter some of the adverse influence of El Niño on the Indian monsoon.ENSO has three phases — El Niño, neutral and La Niña — determined largely by sea-surface temperatures in the equatorial Pacific. An El Niño is declared when the relevant three-month average sea-surface temperature anomaly crosses the prescribed threshold.