Overview
- National forecasts from the Servicio Meteorológico Nacional show a 100% probability of El Niño persistence for Oct–Dec 2026 and NOAA estimates more than an 83% chance the episode will remain strong into Jan–Mar 2027.
- Health authorities increased monitoring after mid-October 2026 reports showed fewer than 1,000 suspected dengue cases with only four laboratory-confirmed infections tied to travel and no validated local transmission.
- Large multi-country studies published in The Lancet Planetary Health and Nature Communications find a clear statistical link between ENSO strength and higher dengue incidence, with one study estimating a roughly 23.7% rise in contagion probability per standard deviation of El Niño intensity.
- Experts stress substantial local uncertainty because extreme rainfall can both create stagnant water that breeds Aedes aegypti and wash away larvae, so local temperatures, water retention, vector-control capacity and household behavior will determine actual outbreak risk.
- El Niño also carries mixed economic and social effects in Argentina, including possible gains for some crop yields and simultaneous flood, infrastructure and displacement risks that can deepen local inequality and test government emergency responses.