El Niño and La Niña are termed as the warm and cold phases of ENSO. El Niño is characterised by above-average sea surface temperatures over the central and eastern equatorial Pacific Ocean. Major historical El Niño events have occurred during the following periods: 1957–58, 1972–73, 1982–83, 1997–98, 2015–16 and 2023-24. Storm activityThe analysis of MMS indicates that during very strong El Niño, cyclone activity over Southwest Indian Ocean (SWIO) is relatively low. Activité cycloniqueHistoriquement, lors d’épisodes de fort El Niño, l’activité cyclonique globale dans le sud-ouest de l’océan Indien est inférieure à la normale.