EL NIÑO, the Weather and the Climate of Uruguay. 2026–2027 outlook

This work analyzes the influence of the El Niño–Southern Oscillation (ENSO) on rainfall and near-surface (2 m) temperature in Uruguay during austral spring and summer, the seasons of greatest climatic sensitivity for the country. Drawing on 75 years of the ERA5 reanalysis (1951–2025) and NOAA's Relative Oceanic Niño Index (RONI), it quantifies — through Pearson correlation and ENSO-phase composites — the response of eighteen representative locations across the national territory, month by month.

Main findings: El Niño is associated with increased rainfall, most markedly in the north and along the river coast, and with milder summers, whereas La Niña tilts the balance toward drought; the teleconnection peaks in late spring (November–December) and weakens in January. A dedicated module examines the effect on sun-and-beach tourism along the Atlantic coast, where El Niño summers tend to be cloudier and less sunny. Case studies of the major events since 1950 — including the anomalous floods of April 1959 — show that oceanic intensity alone does not determine local impact.

The work closes with the outlook for the 2026–2027 season and a guide to interpreting seasonal forecasts. Written for both technical and general readers, it is intended as a decision-support resource for the agricultural, energy, tourism and health sectors. Data sources, methods and figures are documented for reproducibility.

Author: Gabriel Labrador Hernández (PortalMeteo®). All rights reserved. DOI 10.5281/zenodo.20536023