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Grajaú fire, 28 August 2025 Grajaú

Out · last detection 12 Sept 2025, 16:41 UTC

The fire started on 28 August 2025 in Grajaú, Brazil, and satellites saw it burning for 16 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 7,591 hectares from heat detections, spread across a single municipality.

It is the 112th largest in Maranhão since 2016 (of 607 with a page). Number 185 in Brazil in 2025, of 714.

Burnt area
7,591ha
GWIS perimeter (Copernicus)
Duration
16days
28 Aug 2025 – 12 Sept 2025
Municipalities hit
1
municipalities
Started on
28 Aug
2025
Heat detections
293
in a single hotspot: 144 MW
Danger at start
42
Very high · FWI index
Energy released
3.7GW
sum of detected power

Where it burned

12 Sept 2025
HOTSPOTS BY DAY 28 Aug12 Sept

How it evolved, day by day

28293031123456789101112

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

The weather it burned in

38°high
44km/h · peak gust
22%lowest humidity

It had gone 9 days without rain (1 mm or more) when it started.

This area had burned before

95% of the perimeter overlaps earlier fires recorded since 2016: 1,465 ha in 2016, 6,926 ha in 2017, 1,941 ha in 2019, 1,003 ha in 2022. Part of it burned more than once, so the yearly figures add up to more than the 7,202 ha that had burned before.

What happened to each town

  1. Grajaú 73,872 inhabitants where it started
    7,642 ha reached on 21 Aug
    0.9 %

Burnt area inside each municipality, from crossing the GWIS perimeter with administrative boundaries. The distance is from the town centre to the nearest fire: staying a kilometre away does not mean it reached the houses.

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 34.7 °C 31 % 42 km/h 0.0 mm Very high 42
22 Aug 35.2 °C 30 % 41 km/h 0.0 mm Very high 42
23 Aug 35.4 °C 31 % 35 km/h 0.0 mm Very high 39
24 Aug 35.5 °C 28 % 35 km/h 0.0 mm Very high 38
25 Aug 36.0 °C 30 % 40 km/h 0.0 mm Very high 41
26 Aug 35.9 °C 27 % 37 km/h 0.0 mm Very high 41
27 Aug 35.7 °C 26 % 33 km/h 0.0 mm High 38
28 Aug 35.6 °C 28 % 32 km/h 0.0 mm Very high 39
29 Aug 35.4 °C 28 % 36 km/h 0.0 mm Very high 41
30 Aug 36.0 °C 28 % 39 km/h 0.1 mm Very high 43
31 Aug 35.8 °C 26 % 42 km/h 0.0 mm Very high 45
1 Sept 36.1 °C 29 % 42 km/h 0.0 mm Very high 46
2 Sept 36.3 °C 30 % 43 km/h 0.0 mm Very high 46
3 Sept 35.6 °C 29 % 42 km/h 0.0 mm Very high 46
4 Sept 35.8 °C 29 % 40 km/h 0.0 mm Very high 45
5 Sept 35.3 °C 29 % 43 km/h 0.0 mm Very high 48
6 Sept 36.2 °C 31 % 38 km/h 0.0 mm Very high 44
7 Sept 36.6 °C 28 % 36 km/h 0.0 mm Very high 43
8 Sept 36.6 °C 27 % 37 km/h 0.0 mm Very high 45
9 Sept 36.3 °C 28 % 38 km/h 0.0 mm Very high 45
10 Sept 37.1 °C 22 % 30 km/h 0.0 mm Very high 41
11 Sept 36.8 °C 35 % 40 km/h 0.0 mm Very high 40
12 Sept 34.0 °C 46 % 42 km/h 0.5 mm High 31
13 Sept after 34.0 °C 41 % 32 km/h 0.5 mm High 33
14 Sept after 35.1 °C 34 % 37 km/h 0.3 mm High 34
15 Sept after 37.7 °C 23 % 34 km/h 0.0 mm Very high 42
16 Sept after 36.8 °C 29 % 44 km/h 0.0 mm Very high 44
17 Sept after 37.1 °C 30 % 41 km/h 0.0 mm Very high 46
18 Sept after 36.5 °C 33 % 38 km/h 0.0 mm Very high 42
19 Sept after 35.5 °C 38 % 32 km/h 0.1 mm High 36
20 Sept after 33.7 °C 48 % 29 km/h 0.2 mm High 30
21 Sept after 34.6 °C 41 % 34 km/h 0.1 mm High 31
22 Sept after 33.6 °C 47 % 35 km/h 0.4 mm High 34
23 Sept after 36.4 °C 39 % 35 km/h 0.1 mm High 31
24 Sept after 36.1 °C 37 % 36 km/h 0.1 mm High 32
25 Sept after 36.6 °C 30 % 33 km/h 0.0 mm High 36
26 Sept after 35.7 °C 31 % 29 km/h 0.0 mm High 35
27 Sept after 36.8 °C 25 % 37 km/h 0.0 mm Very high 43
28 Sept after 36.5 °C 28 % 34 km/h 0.0 mm Very high 42

Before and after, from space

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

Before · 21 Aug 2025
After · 19 Sept 2025

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 11 September 2025 the air beside the fire reached 55 µg/m³ of PM2.5. That day averaged 36: 2.4 times the WHO daily guideline (15).

PM2.5 peak55 µg/m³
Days over the guideline9 days
PM1056 µg/m³
Optical depth0.52
19202122232425262728293031123456789101112131415161718192021
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 · 293Every 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?
GWIS (Copernicus) dates it between 28 August 2025 and 12 September 2025: 16 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 7,591 hectares (75.9 km²). It is an estimate: official national figures may differ.
Which municipalities burned?
The fire only entered Grajaú (7,642 ha, 0.9 %).
What was the weather like?
During the fire the temperature reached 37.7 °C, humidity dropped to 22 % and gusts hit 44 km/h. The fire danger index (FWI) reached 48, 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

Satellite cross-check

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.

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.