Boca do Acre fire, 21 August 2021 Boca do Acre
The fire started on 21 August 2021 in Boca do Acre, Brazil, and satellites saw it burning for 9 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 5,098 hectares from heat detections, spread across a single municipality.
It is the 156th largest in Amazonas since 2016 (of 450 with a page). Number 384 in Brazil in 2021, of 814.
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- Burnt area
- 5,098ha
- GWIS perimeter (Copernicus)
- Duration
- 9days
- 21 Aug 2021 – 29 Aug 2021
- Municipalities hit
- 1
- municipalities
- Started on
- 21 Aug
- 2021
- Heat detections
- 324
- in a single hotspot: 985 MW
- Danger at start
- 29
- High · FWI index
- Average daily power
- 1.3GW
- 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 53 days without rain (1 mm or more) when it started. Rain came after the fire: 3.8 mm on 30 Aug.
This area had burned before
71% of the perimeter overlaps earlier fires recorded since 2016: 570 ha in 2016, 427 ha in 2018, 2,490 ha in 2019, 1,676 ha in 2020. Part of it burned more than once, so the yearly figures add up to more than the 3,617 ha that had burned before.
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
-
5,134 ha reached on 21 Aug0.2 %
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 2020Inside the perimeter there was no noticeable built-up land and almost nobody lived there (GHSL 2020, 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.
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) |
|---|---|---|---|---|---|
| 21 Aug | 35.2 °C | 41 % | 19 km/h | 0.1 mm | High 29 |
| 22 Aug | 33.6 °C | 49 % | 20 km/h | 0.0 mm | High 25 |
| 23 Aug | 34.8 °C | 43 % | 29 km/h | 0.0 mm | High 26 |
| 24 Aug | 35.2 °C | 39 % | 27 km/h | 0.0 mm | High 27 |
| 25 Aug | 36.0 °C | 40 % | 39 km/h | 0.0 mm | High 31 |
| 26 Aug | 35.6 °C | 41 % | 30 km/h | 0.2 mm | High 29 |
| 27 Aug | 32.4 °C | 47 % | 26 km/h | 2.5 mm | Low 11 |
| 28 Aug | 32.1 °C | 50 % | 29 km/h | 0.2 mm | Moderate 18 |
| 29 Aug | 33.3 °C | 49 % | 27 km/h | 0.2 mm | Moderate 21 |
| 30 Aug after | 31.4 °C | 59 % | 32 km/h | 3.8 mm | Very low 4 |
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.
Detections table · 324Every satellite heat detection, one by one, with time, satellite, power and coordinates.
| Date and time | Satellite | FRP (MW) | Lat | Lon |
|---|
Other fires nearby
Frequently asked questions
- How long did the Boca do Acre fire last?
- According to the heat detections seen by satellite inside the perimeter, it burned from 21 August 2021 to 29 August 2021 (9 days). The perimeter dates it from 21 August 2021 to 27 August 2021.
- How much area did it burn?
- The perimeter GWIS (Copernicus) rebuilt from heat detections is 5,098 hectares (51.0 km²). It is an estimate: official national figures may differ.
- Which municipalities burned?
- The fire only entered Boca do Acre (5,134 ha, 0.2 %).
- What was the weather like?
- During the fire the temperature reached 36.0 °C, humidity dropped to 39 % and gusts hit 39 km/h. The fire danger index (FWI) reached 31, class High.
- Where does this data come from?
- From the GWIS (Copernicus) burnt perimeter, NASA FIRMS VIIRS hotspots and the administrative boundaries of Brazil (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: 193 · Emergency number and official warnings ›
Satellite cross-check
History of this page · 1 Changes in area, dates, name, official record or merged pages, compared every night since 24 October 2026.
- Last day with fire: 27 August 2021 → 29 August 2021.
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 adjusted with the VIIRS detections inside the perimeter, which said 21 August 2021 to 27 August 2021. 324 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 2020, 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.