Formosa fire, September 2023 Formosa, Pilcomayo
The fire started on 17 September 2023 in Formosa, Argentina, and satellites saw it burning for 2 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 1,771 hectares from heat detections, spread across 2 municipalities.
It is the 458th largest in Formosa since 2016 (of 620 with a page). Number 135 in Argentina in 2023, of 180.
The power measured by the satellite is low (16.2 MW in the strongest hotspot), more typical of grass or stubble burning, or a slow surface fire, than of a large crown fire.
Compare with…
- Burnt area
- 1,771ha
- GWIS perimeter (Copernicus)
- Duration
- 2days
- 17 Sept 2023 – 18 Sept 2023
- Municipalities hit
- 2
- departments
- Started on
- 17 Sept
- 2023
- Heat detections
- 47
- in a single hotspot: 16 MW
- Danger at start
- 16
- Moderate · FWI index
- Average daily power
- 116MW
- detected power per day, on average
Where it burned
How it evolved, day by day
Fire radiative power detected each day, in megawatts, and number of hotspots. The magenta bar marks the peak day.
The weather it burned in
It had gone 3 days without rain (1 mm or more) when it started. Rain came after the fire: 10.3 mm on 19 Sept.
This area had burned before
96% of the perimeter overlaps earlier fires recorded since 2016: 466 ha in 2016, 45 ha in 2018, 1,286 ha in 2019, 1,265 ha in 2020, 1,434 ha in 2022. Part of it burned more than once, so the yearly figures add up to more than the 1,708 ha that had burned before.
- 1,434 ha Pilcomayo fire, January 2022 81,287 ha in total; the hectares shown are those it shares with this fire
- 1,145 ha Formosa fire, February 2019 3,746 ha in total; the hectares shown are those it shares with this fire
- 921 ha Formosa fire, September 2020 4,767 ha in total; the hectares shown are those it shares with this fire
- 250 ha Formosa fire, October 2020 3,413 ha in total; the hectares shown are those it shares with this fire
- 45 ha Pilcomayo fire, September 2018 1,525 ha in total; the hectares shown are those it shares with this fire
How big is it?
London boundary: geoBoundaries · Office for National Statistics (Open Government Licence v3.0).
Paris boundary: geoBoundaries · Institut national de l'information géographique et forestière (IGN-F) (Etalab Open License 2.0).
Madrid boundary: geoBoundaries · Open Data ESRI, IGN Central Registry of Cartography Area (CC BY 4.0).
Berlin boundary: geoBoundaries · Federal Agency for Cartography and Geodesy (dl-de/by-2-0).
This compares size, not location: both shapes are at the same scale, north up, centred on each other.
What happened to each town
-
Formosa where it started1,702 ha reached on 17 Sept0.3 %
-
72 ha reached on 17 Sept0.0 %
Burnt area inside each municipality, from crossing the GWIS perimeter with administrative boundaries. The distance runs from the point marking the centre of each area to the nearest fire: staying a kilometre away does not mean it reached the houses.
People and buildings inside the perimeter
GHSL 2025Inside the perimeter there was no noticeable built-up land and almost nobody lived there (GHSL 2025, satellite-based estimate).
This is an estimate on 100 m cells, made from satellite imagery and census data: it does not mean that homes burned or that anyone was harmed. The perimeter also contains land that never burned. The GHSL 2025 epoch is a projection made from 2020 and earlier data.
Source: Global Human Settlement Layer (GHS-BUILT-S and GHS-POP R2023A), European Commission Joint Research Centre (JRC), © European Union, CC BY 4.0. Sum inside the perimeter computed by WorldFires. human-settlement.emergency.copernicus.eu
The weather day by day
ECMWF ERA5 reanalysis at the fire location, the standard reference for past weather, and the Canadian Fire Weather Index (the same system Copernicus uses), computed by WorldFires from that data. Days after the fire run until the first rain.
Open-Meteo.com (CC BY 4.0) · Copernicus Climate Change Service (ERA5)
| Day | High | Min. humidity | Peak gust | Rain | Danger (FWI) |
|---|---|---|---|---|---|
| 17 Sept | 37.6 °C | 35 % | 59 km/h | 0.0 mm | Moderate 16 |
| 18 Sept | 32.4 °C | 47 % | 52 km/h | 0.3 mm | Moderate 12 |
| 19 Sept after | 25.6 °C | 63 % | 42 km/h | 10.3 mm | Very low 0 |
Before and after, from space
Drag the line to compare the same ground before the fire and after it.
If the day is cloudy, change the date: each satellite passes once a day. In false colour the burnt ground looks brown or red.
The smoke
CAMS · CopernicusOn 20 September 2023 the air beside the fire reached 25 µg/m³ of PM2.5. That day averaged 20: 1.4 times the WHO daily guideline (15).
Particles from the Copernicus CAMS model at the centre of the perimeter; these are not measurements in each town. The pale bar is the worst hour, the solid one the daily average.
Open-Meteo.com (CC BY 4.0) · Copernicus Atmosphere Monitoring Service (CAMS)
Detections table · 47Every satellite heat detection, one by one, with time, satellite, power and coordinates.
| Date and time | Satellite | FRP (MW) | Lat | Lon |
|---|
Other fires nearby
- 81,287 haPilcomayo5 January 2022 · 29 days · 9 km away
- 23,802 haFormosa11 March 2024 · 11 days · 10 km away
- 12,890 haFormosa16 February 2026 · 7 days · 33 km away
- 16,214 haPilcomayo10 March 2024 · 17 days · 34 km away
- 5,616 haPilcomayo7 January 2022 · 17 days · 37 km away
- 13,234 haPirané19 September 2020 · 20 days · 39 km away
Frequently asked questions
- How long did the Formosa fire last?
- GWIS (Copernicus) dates it between 17 September 2023 and 18 September 2023: 2 days between the first and last heat detection of the perimeter.
- How much area did it burn?
- The perimeter GWIS (Copernicus) rebuilt from heat detections is 1,771 hectares (17.7 km²). It is an estimate: official national figures may differ.
- Which municipalities burned?
- The fire entered 2 municipalities: Formosa (1,702 ha, 0.3 %); Pilcomayo (72 ha, 0.0 %).
- What was the weather like?
- During the fire the temperature reached 37.6 °C, humidity dropped to 35 % and gusts hit 59 km/h. The fire danger index (FWI) reached 16, class Moderate.
- Where does this data come from?
- From the GWIS (Copernicus) burnt perimeter, NASA FIRMS VIIRS hotspots and the administrative boundaries of Argentina (geoBoundaries). It is not an official report.
Where to verify it
A satellite detection is not an official report. Final figures and the fire’s status are published by each country’s emergency service.
Emergency number: 911 · 100 · Emergency number and official warnings ›
Satellite cross-check
History of this page Changes in area, dates, name, official record or merged pages, compared every night since 24 October 2026.
No changes since 24 October 2026.
Does something look wrong on this page?
This page is built from satellite data and official records, and it sometimes gets things wrong: the wrong dates, the wrong town, two fires merged into one, or something that was not a wildfire at all. If you know this fire first-hand (you live nearby, saw it, fought it or reported on it), tell us what really happened and we will check it.
Report an error
How we know this
- Perimeter: GWIS (Copernicus), rebuilt from heat detections rather than mapped on imagery.
- Dates from the perimeter: the VIIRS detections inside it did not change them. 47 Suomi-NPP VIIRS detections on those dates.
- We have not matched this page with any official record.
- Weather: Copernicus ERA5 reanalysis at the fire location, in cells of about 25 km.
- Built-up area and population come from the JRC Global Human Settlement Layer (epoch 2025, 100 m cells), summed inside the perimeter: an estimate of what was there, not a damage count.
Where this data comes from
The perimeter comes from the Copernicus Global Wildfire Information System (GWIS), which rebuilds it from MODIS and VIIRS heat detections and publishes it under CC BY 4.0. It is not measured on imagery as in Europe, so it is an estimate. Heat detections come from the VIIRS sensors aboard Suomi-NPP and NOAA-20, distributed by NASA FIRMS at 375 m resolution. Municipal boundaries come from geoBoundaries ADM2 (Creative Commons Attribution 3.0 Intergovernmental Organisations (CC BY 3.0 IGO)). The area per municipality is computed by WorldFires by crossing the perimeter with those boundaries, so it may differ from each country’s official figure.