National meteorological services across South America have issued a cascade of alerts this week, warning of severe storms, heavy snowfall and a sudden temperature plunge that could affect millions of people from the Andes to the southern cone. In Argentina, the National Meteorological Service (SMN) declared a red alert for the Neuquén cordillera, where a historic cyclone is expected to bring 48 hours of hail, rain and wind gusts, with temperatures falling to 3°C. Orange and yellow alerts for snow, rain and the hot, dry Zonda wind cover seven provinces, with accumulations of up to 60 cm of snow and gusts exceeding 100 km/h forecast in high-altitude areas.

In neighbouring Brazil, the National Institute of Meteorology (Inmet) and the São Paulo emergency management centre (CGE) reported that a persistent atmospheric block will keep the southeast dry and cold, with overnight lows of 9°C in the capital and humidity dropping below 50%. The greater risk, however, lies in the southern state of Rio Grande do Sul, where a combination of a semi-stationary front, a low-pressure system and a strong moisture feed from the Amazon is expected to produce days of heavy rain, hail and winds above 90 km/h from 16 to 25 July. Forecasters there warn of accumulated rainfall between 200 and 400 mm, raising the threat of flooding and landslides.

These immediate hazards are unfolding against the backdrop of a strengthening El Niño. The US Climate Prediction Center now puts the probability of a “very strong” event at 81% for the October–December period, with a 97% chance it persists into early 2027. In Argentina, meteorologists anticipate that the phenomenon will bring episodes of extreme rainfall—up to 300 mm in a single day—to the north-east and central regions from August onwards, while Colombian authorities warn of reduced rainfall and heightened fire risk in the Caribbean and Andean zones. Mexican analysts, meanwhile, point to the risk of drought and pressure on food prices, recalling the 14% drop in agricultural output during the 1997–98 El Niño.

Despite the convergence of warnings, significant uncertainty remains. Brazilian meteorologists note that the current storms in Rio Grande do Sul are not solely attributable to El Niño, as the ocean-atmosphere coupling is not yet fully established. In Argentina, the exact track and intensity of the approaching cyclone are still being refined, and authorities have urged residents to secure loose objects, avoid outdoor activities and prepare emergency kits. No casualties or major damage have been reported as of Wednesday, but emergency services across the region remain on high alert, with monitoring continuing around the clock.