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Grajaú fire, 29 August 2023 Arame, Grajaú, Amarante do Maranhão

Out · last detection 22 Sept 2023, 16:58 UTC

The fire started on 29 August 2023 in Grajaú, Brazil, and satellites saw it burning for 25 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 5,700 hectares from heat detections, spread across 3 municipalities.

It is the 181th largest in Maranhão since 2016 (of 607 with a page). Number 137 in Brazil in 2023, of 431.

Compare with…

Suggestions: Arame · 2019Arame · 2017Amarante do Maranhão · 2016Amarante do Maranhão · 2017

Burnt area
5,700ha
GWIS perimeter (Copernicus)
Duration
25days
29 Aug 2023 – 22 Sept 2023
Municipalities hit
3
municipalities
Started on
29 Aug
2023
Heat detections
193
in a single hotspot: 167 MW
Danger at start
30
High · FWI index
Average daily power
160MW
detected power per day, on average

Where it burned

HOTSPOTS BY DAY 29 Aug22 Sept
22 Sept 2023

How it evolved, day by day

31 Aug 2023 · 1 MW · 1 1 Sept 2023 · 1 MW · 1 4 Sept 2023 · 14 MW · 2 5 Sept 2023 · 60 MW · 4 6 Sept 2023 · 215 MW · 8 7 Sept 2023 · 10 MW · 2 9 Sept 2023 · 20 MW · 3 10 Sept 2023 · 579 MW · 45 11 Sept 2023 · 23 MW · 9 12 Sept 2023 · 273 MW · 12 13 Sept 2023 · 408 MW · 33 14 Sept 2023 · 76 MW · 16 15 Sept 2023 · 1,071 MW · 36 16 Sept 2023 · 17 MW · 11 17 Sept 2023 · 12 MW · 1 18 Sept 2023 · 94 MW · 7 19 Sept 2023 · 3 MW · 1 22 Sept 2023 · 5 MW · 1
31 Aug 5 Sept 9 Sept 12 Sept 15 Sept 18 Sept

Fire radiative power detected each day, in megawatts, and number of hotspots. The magenta bar marks the peak day.

The weather it burned in

36°high
49km/h · peak gust
29%lowest humidity

It had gone more than two months without rain (1 mm or more) when it started.

This area had burned before

66% of the perimeter overlaps earlier fires recorded since 2016: 2,582 ha in 2016, 1,000 ha in 2017, 3,160 ha in 2019. Part of it burned more than once, so the yearly figures add up to more than the 3,755 ha that had burned before.

How big is it?

10 km
It burned the equivalent of 3.6% of the area of London (57 km² against 1,583 km²).

London boundary: geoBoundaries · Office for National Statistics (Open Government Licence v3.0).

This compares size, not location: both shapes are at the same scale, north up, centred on each other.

What happened to each town

  1. Arame 25,517 inhabitants
    3,496 ha reached on 5 Sept
    1.2 %
  2. Grajaú 73,872 inhabitants where it started
    1,134 ha reached on 31 Aug
    0.1 %
  3. Amarante do Maranhão 37,085 inhabitants
    1,109 ha reached on 15 Sept
    0.2 %

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 2025
Built-up area0.51 ha
Residents≈ 100

Inside the perimeter there were about 0.51 hectares of built-up land and about 100 residents (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)
29 Aug 33.7 °C 42 % 34 km/h 0.0 mm High 30
30 Aug 33.8 °C 46 % 27 km/h 0.2 mm High 27
31 Aug 33.6 °C 45 % 26 km/h 0.4 mm High 28
1 Sept 32.0 °C 51 % 32 km/h 0.3 mm High 28
2 Sept 32.7 °C 44 % 34 km/h 0.3 mm High 30
3 Sept 33.2 °C 42 % 32 km/h 0.2 mm High 29
4 Sept 34.4 °C 35 % 34 km/h 0.2 mm High 32
5 Sept 34.8 °C 32 % 35 km/h 0.0 mm High 33
6 Sept 33.1 °C 43 % 37 km/h 0.0 mm High 31
7 Sept 34.1 °C 32 % 49 km/h 0.2 mm High 37
8 Sept 33.3 °C 38 % 41 km/h 0.1 mm High 37
9 Sept 35.2 °C 32 % 39 km/h 0.0 mm High 37
10 Sept 35.2 °C 30 % 42 km/h 0.0 mm Very high 40
11 Sept 34.2 °C 39 % 38 km/h 0.0 mm Very high 38
12 Sept 34.2 °C 37 % 47 km/h 0.1 mm High 37
13 Sept 35.8 °C 29 % 40 km/h 0.0 mm Very high 39
14 Sept 34.9 °C 41 % 41 km/h 0.1 mm High 36
15 Sept 36.0 °C 32 % 33 km/h 0.0 mm High 34
16 Sept 34.5 °C 38 % 40 km/h 0.0 mm Very high 39
17 Sept 34.5 °C 35 % 38 km/h 0.0 mm High 37
18 Sept 34.8 °C 35 % 32 km/h 0.0 mm High 34
19 Sept 35.9 °C 30 % 45 km/h 0.0 mm High 38
20 Sept 35.5 °C 36 % 36 km/h 0.1 mm High 35
21 Sept 36.3 °C 29 % 38 km/h 0.0 mm High 37
22 Sept 35.8 °C 30 % 37 km/h 0.0 mm Very high 38
23 Sept after 35.7 °C 35 % 35 km/h 0.0 mm Very high 38
24 Sept after 36.3 °C 35 % 44 km/h 0.0 mm Very high 39
25 Sept after 36.5 °C 33 % 34 km/h 0.0 mm High 37
26 Sept after 33.9 °C 43 % 29 km/h 0.0 mm High 32
27 Sept after 34.3 °C 46 % 26 km/h 0.4 mm High 30
28 Sept after 34.3 °C 40 % 34 km/h 0.0 mm High 34
29 Sept after 36.1 °C 33 % 32 km/h 0.0 mm High 34
30 Sept after 35.8 °C 36 % 30 km/h 0.0 mm High 35
1 Oct after 36.1 °C 36 % 28 km/h 0.1 mm High 37
2 Oct after 35.7 °C 35 % 36 km/h 0.0 mm High 36

Before and after, from space

Drag the line to compare the same ground before the fire and after it.

Before · 22 Aug 2023
After · 29 Sept 2023

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 · Copernicus

On 15 September 2023 the air beside the fire reached 28 µg/m³ of PM2.5. That day averaged 16: 1.1 times the WHO daily guideline (15).

PM2.5 peak28 µg/m³
Days over the guideline1 day
PM1040 µg/m³
Optical depth0.48
345678910111213141516171819202122
Good Fair Moderate Poor Very poor Extremely poor

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 · 193Every satellite heat detection, one by one, with time, satellite, power and coordinates.
⬇ Download CSV Times in UTC. Each detection is a 375 m pixel: a large fire yields hundreds per pass.
Date and timeSatelliteFRP (MW)LatLon

Other fires nearby

All fires in Brazil ›

Frequently asked questions

How long did the Grajaú fire last?
According to the heat detections seen by satellite inside the perimeter, it burned from 29 August 2023 to 22 September 2023 (25 days). The perimeter dates it from 5 September 2023 to 19 September 2023.
How much area did it burn?
The perimeter GWIS (Copernicus) rebuilt from heat detections is 5,700 hectares (57.0 km²). It is an estimate: official national figures may differ.
Which municipalities burned?
The fire entered 3 municipalities: Arame (3,496 ha, 1.2 %); Grajaú (1,134 ha, 0.1 %); Amarante do Maranhão (1,109 ha, 0.2 %).
What was the weather like?
During the fire the temperature reached 36.3 °C, humidity dropped to 29 % and gusts hit 49 km/h. The fire danger index (FWI) reached 40, class Very 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 · 2 Changes in area, dates, name, official record or merged pages, compared every night since 24 October 2026.
  1. Last day with fire: 19 September 2023 → 22 September 2023.
  2. Start date: 5 September 2023 → 29 August 2023.

RSS Changes to this page

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
What do you think is wrong?

We will only use your email to reply about this report. Privacy. This is not an emergency service: if there is a fire now, call 193.

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 5 September 2023 to 19 September 2023. 193 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.

How we build fire pages: methodology ›

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.