# Weather instability in Santiago and Biobío, Chile > Live situation record from CLSTR: https://clstr.news/situations/weather-instability-in-santiago-chile > Updated: 2026-09-25T11:01:05.000Z. Sources: 36. Developments: 2. Weather patterns in Santiago, Chile, are transitioning from a heatwave to a period of instability. An atmospheric river is expected to bring increased rainfall to the Metropolitan Region, with potential accumulations between 3 and 15 mm that may persist through early next week. Beyond the capital, meteorological shifts are impacting other parts of Chile. Senapred has issued a “Preventive Early Warning” for the Biobío Region, where wind speeds could reach 80 km/h and rainfall may range between 2 and 50 mm. In Coronel, heavy rain and wind have already forced the early closure of local festivities. Recent forecasts for Santiago indicate that following a weekend of cloudy skies and pleasant temperatures, rain is expected to return to the Metropolitan Region on Monday, September 28. Meteorologist Jaime Leyton anticipates that instability in the central-south zone will trigger showers starting in the late afternoon. This precipitation is predicted to be irregularly distributed, with little to no rain in the western sector, while showers are expected from central Santiago toward the east. ## Timeline ### 2026-09-25: South American agriculture faces extreme heat and El Niño weather shifts Extreme heat waves are hitting Paraguay with temperatures up to 43°C, while El Niño threatens Argentina's northeast with excessive spring rains and potential agricultural disruptions. 33 sources. https://clstr.news/cluster/santiago-weather-forecast-predicts-rain-for-monday ### 2026-09-06: Santiago weather forecast predicts return of rain and cooler temperatures Santiago expects cooler temperatures and a return of rain this week, with high probabilities of showers in mountain areas by Thursday due to a coastal trough. 3 sources. https://clstr.news/cluster/santiago-weather-forecast-predicts-return-of-rain-and-cooler-temperatures --- Cite as: Weather instability in Santiago and Biobío, Chile. CLSTR, https://clstr.news/situations/weather-instability-in-santiago-chile