Introduction
In late December 2025, a wildfire affected Santiago’s foothills amid high temperatures, low humidity and wind favouring rapid spread.
Satellite-detected hotspots show where the fire burned—but the meteorological hazard had begun earlier.
Days before the event, our FWI-WRF pipeline was already highlighting weather conditions favourable to complex fires across parts of the Andes and the urban–wildland interface in the Metropolitan Region.
The weather did not start the ignition. But it framed the atmospheric setting in which a fire could grow quickly.
What satellites show
Each point corresponds to satellite heat signatures from MODIS and VIIRS between 30 December 2025 and 2 January 2026.
Over four days, 408 satellite detections were recorded in central Chile. The densest cluster sat in the foothills east of Santiago, where multiple hotspots exceeded 400 K brightness temperature.
This is not smoke alone—it is active fire seen from space.
Anticipation is not prediction
The Fire Weather Index (FWI) is the international standard for summarising how conducive the atmosphere is to large wildfires. It combines temperature, relative humidity, wind and accumulated precipitation into a single meteorological danger index.
Our FWI-WRF system uses high-resolution weather forecasts to estimate that risk with lead time of days. That does not mean “predicting ignitions”—it means flagging when the landscape enters an atmospheric regime where a fire can spread faster, intensify and become harder to suppress.
In the days leading up to this event, FWI-WRF already showed Very High and Extreme categories over parts of the Metropolitan foothills.
What changes when you watch the risk
Satellites show the fire while it is happening; meteorological indices help surface the conditions that make it more dangerous sooner. Pairing atmospheric forecasts with satellite observation supports an operational view of risk before, during and after the event.
That is the purpose of FWI-WRF.
FWI-WRF derives the Fire Weather Index from weather forecasts produced with the WRF model. Heat detections come from NASA FIRMS products using MODIS and VIIRS sensors. Brightness temperature represents the radiative intensity observed by the satellite for each active detection.