Seasonal forecasts as public health tools: Preparing Latin America for the 2026 El Niño

Abstract

The tropical Pacific is signalling the development of a likely moderate (with possibilities of strong) El Niño event by mid-2026. As of June 2026, the C3S multi-system shows most Niño 3.4 sea-surface temperature forecasted relative anomalies (vs 1991–2020 period) falling between 2.3 °C and 3.9 °C by December 2026, with more than 50% of the models exceeding 3 °C amplitude [1] (the 2015/16 anomaly reached 3 °C [2]). NOAA’s Climate Prediction Center indicates El Niño is likely to emerge (82% chance) in May-July, lasting until the end of 2026 and beginning of 2027 [3], whilst the IRI/Columbia plume forecasts sustain probabilities of 72–80% [4]. Although these early forecasts are still associated with large uncertainties, there is a strong consensus of a warming signal and that El Niño conditions are likely to develop in May-July and maintained over 2026–27.