However, even during this period, it does have some impact, such as suppressing June-September monsoon rainfall in India. How was its impact on rainfall elsewhere? The following four maps explain this.
Because it is yet to reach its peak, this is also the period when its impact on global weather is not expected to be very strong. The 2026 El Nino that started in May has now been in place for five full months.
A brief explanation of El Nino is useful in assessing its impact on rainfall. It is described as a cyclical warming of the central-eastern equatorial Pacific Ocean. This can be seen in the streak of warmer-than-normal sea surface temperatures (SSTs) along the equator, running from the Americas to the central region of the Pacific Ocean. The warm SSTs in the central-eastern Pacific Ocean lead to lower-than-normal air pressure above the region. This aids the formation of clouds. A crude explanation for this is that warm SSTs aid the formation of water vapour, which rises up to fill in the space in the atmosphere being created by lower air pressure. In contrast, the cooler-than-normal SSTs in the western Pacific lead to higher-than-normal air pressure there, which suppresses cloud formation.
As expected from the contrast between the eastern and western halves of the equatorial Pacific described above, an El Nino increases rainfall in the western parts of the two Americas. On the other hand, countries like Indonesia, Malaysia, and the eastern half of Australia — which are west of the Pacific — see lower rainfall than usual. To be sure, it is possible that there were more years affected by an El Nino during this period. The accompanying map only shows the deviation for years when the May-September period averaged El Nino levels of warming in the central-eastern Pacific. To be sure, as the map suggests, El Nino’s impact on rain does not have a neat east-west division. Parts of China, for example, have averaged more than normal rain even during El Nino years. Similarly, parts of India have also averaged more than normal rain in such years, although overall monsoon rain is generally suppressed.
Because el Nino is not the only phenomenon that affects rain, this is. This can be seen in rainfall’s average deviation from normal in the eight El Nino years during the 1979-2025 period for which rainfall data is available.
