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BR · Brazil · –

Nazaré do Piauí fire, September 2021 São José do Peixe, Nazaré do Piauí, São Francisco do Piauí

Out · last detection 23 Sept 2021, 16:26 UTC

The fire started on 3 September 2021 in Nazaré do Piauí, Brazil, and satellites saw it burning for 21 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 12,693 hectares from heat detections, spread across 4 municipalities.

It is the 64th largest in Piaui since 2016 (of 665 with a page). Number 115 in Brazil in 2021, of 814.

Burnt area
12,693ha
GWIS perimeter (Copernicus)
Duration
21days
3 Sept 2021 – 23 Sept 2021
Municipalities hit
4
municipalities
Started on
3 Sept
2021
Heat detections
569
in a single hotspot: 118 MW
Danger at start
56
Extreme · FWI index
Average daily power
247MW
detected power per day, on average

Where it burned

HOTSPOTS BY DAY 3 Sept23 Sept
23 Sept 2021

How it evolved, day by day

3 Sept 2021 · 111 MW · 11 4 Sept 2021 · 94 MW · 7 5 Sept 2021 · 40 MW · 5 6 Sept 2021 · 171 MW · 22 7 Sept 2021 · 354 MW · 30 8 Sept 2021 · 269 MW · 57 9 Sept 2021 · 86 MW · 10 10 Sept 2021 · 287 MW · 59 11 Sept 2021 · 617 MW · 46 12 Sept 2021 · 484 MW · 38 13 Sept 2021 · 34 MW · 8 15 Sept 2021 · 50 MW · 8 16 Sept 2021 · 60 MW · 16 17 Sept 2021 · 291 MW · 25 18 Sept 2021 · 999 MW · 62 19 Sept 2021 · 638 MW · 75 20 Sept 2021 · 99 MW · 28 21 Sept 2021 · 146 MW · 36 22 Sept 2021 · 67 MW · 17 23 Sept 2021 · 50 MW · 9
3 Sept 7 Sept 11 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

38°high
44km/h · peak gust
18%lowest humidity

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

This area had burned before

71% of the perimeter overlaps earlier fires recorded since 2016: 3,775 ha in 2016, 6,844 ha in 2018, 2,027 ha in 2020. Part of it burned more than once, so the yearly figures add up to more than the 9,055 ha that had burned before.

How big is it?

10 km
It burned the equivalent of 8% of the area of London (127 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. São José do Peixe 3,297 inhabitants
    11,439 ha reached on 3 Sept
    8.8 %
  2. Nazaré do Piauí 6,665 inhabitants where it started
    599 ha reached on 3 Sept
    0.4 %
  3. São Francisco do Piauí 5,392 inhabitants
    544 ha reached on 6 Sept
    0.4 %
  4. Flores do Piauí 4,414 inhabitants
    315 ha reached on 19 Sept
    0.3 %

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 2020
Built-up area0.55 ha
Residents≈ 50

Inside the perimeter there were about 0.55 hectares of built-up land and about 50 residents (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)

Started with Extreme FWI: 46 % of the area in Brazil 60 days without rain: 55 % of the area in Brazil

Day High Min. humidity Peak gust Rain Danger (FWI)
3 Sept 36.8 °C 22 % 43 km/h 0.0 mm Extreme 56
4 Sept 38.0 °C 27 % 41 km/h 0.0 mm Extreme 51
5 Sept 38.0 °C 24 % 35 km/h 0.0 mm Very high 48
6 Sept 37.8 °C 28 % 31 km/h 0.0 mm Very high 47
7 Sept 38.5 °C 18 % 34 km/h 0.0 mm Very high 48
8 Sept 36.6 °C 24 % 43 km/h 0.0 mm Extreme 53
9 Sept 37.4 °C 25 % 39 km/h 0.0 mm Very high 48
10 Sept 38.1 °C 23 % 31 km/h 0.0 mm Very high 44
11 Sept 37.8 °C 23 % 35 km/h 0.0 mm Very high 50
12 Sept 37.3 °C 19 % 39 km/h 0.0 mm Extreme 53
13 Sept 37.1 °C 22 % 44 km/h 0.0 mm Extreme 57
14 Sept 36.9 °C 25 % 42 km/h 0.0 mm Very high 49
15 Sept 37.5 °C 25 % 37 km/h 0.0 mm Very high 49
16 Sept 37.2 °C 21 % 41 km/h 0.0 mm Extreme 52
17 Sept 37.0 °C 22 % 44 km/h 0.0 mm Extreme 58
18 Sept 36.6 °C 21 % 44 km/h 0.0 mm Extreme 56
19 Sept 37.8 °C 23 % 34 km/h 0.0 mm Very high 45
20 Sept 38.0 °C 22 % 24 km/h 0.0 mm Very high 41
21 Sept 37.9 °C 22 % 38 km/h 0.0 mm Very high 49
22 Sept 37.9 °C 25 % 30 km/h 0.0 mm Very high 40
23 Sept 37.3 °C 27 % 34 km/h 0.0 mm Extreme 53
24 Sept after 36.1 °C 29 % 48 km/h 0.0 mm Extreme 54
25 Sept after 36.3 °C 30 % 48 km/h 0.0 mm Extreme 50
26 Sept after 37.0 °C 28 % 44 km/h 0.0 mm Very high 50
27 Sept after 37.0 °C 25 % 41 km/h 0.0 mm Very high 49
28 Sept after 37.5 °C 22 % 45 km/h 0.0 mm Extreme 52
29 Sept after 36.6 °C 26 % 37 km/h 0.0 mm Very high 49
30 Sept after 35.4 °C 37 % 27 km/h 0.0 mm Very high 41
1 Oct after 34.8 °C 43 % 27 km/h 0.9 mm High 23
2 Oct after 36.0 °C 30 % 34 km/h 0.9 mm High 24
3 Oct after 36.7 °C 25 % 36 km/h 0.0 mm Very high 42

Its twins: fires that started in the same weather

It started with an FWI of 55.7, a minimum humidity of 22% and more than two months without rain. Fires in the area that started in weather like this since 2016: 27.

FWI at the start 55.7
Minimum humidity 22 %
Days without rain 60+
this fire chosen twins rest of the area
Almost identicalSimilar

Outlines of the closest twins

Ribeira do Piauí fire, August 2025
8,183 ha 13 days FWI 55.0 Min. humidity 22 % 30 km away, in 2025

First rain (1 mm or more) after it ended: none in the following ten days.

What happened to them

16 days
median duration
4,975 ha
median area
19 %
went past 10,000 ha
1.6 mm
rain at the end (median; 7 of 27 had it)

It was 2.6 times larger than the median of its twins and lasted 21 days, against 16 days.

Only 2 of its 27 twins burned more. The weather on the first day does not explain everything: the wind in the following days, the fuel and the firefighting also count. In 20 of 27, not even 1 mm fell in the ten days after the end: they went out without rain. In the rest, the first rainy day brought a median of 1.6 mm.

This is a bank of analogues: it shows what usually happens, not what will happen. With fewer than 15 twins we give no figures. How we calculate it

How it ended

—first rain
—no rain in ten days
44km/h · max. gust

It was considered over on 23 Sept, and not even 1 mm fell in the following ten days: it went out without rain. Twins with rain when they ended: 7 of 27, with a median of 1.6 mm.

Weather on this page: Open-Meteo.com (CC BY 4.0) · Copernicus Climate Change Service (ERA5)

How a twin is chosen

  • Same area: fires that have already ended, less than 250 km from this one, since 2016.
  • Same start: we compare the FWI on the first day, the minimum humidity that day and the run of days without rain before it. The slider sets how much they may differ.
  • Only pages with final weather data (ERA5 reanalysis) calculated in the same way as this fire’s; agricultural and grass burns and pages with data under review are left out.
  • Fires burning at the same time as this one (a week before or after) are left out: they share the same spell of weather and do not count as a precedent.
  • They are sorted by similarity, and the outlines of the first five are drawn.

How we calculate it

Before and after, from space

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

Before · 27 Aug 2021
After · 30 Sept 2021

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 · 569Every 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 Nazaré do Piauí fire last?
GWIS (Copernicus) dates it between 3 September 2021 and 23 September 2021: 21 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 12,693 hectares (126.9 km²). It is an estimate: official national figures may differ.
Which municipalities burned?
The fire entered 4 municipalities: São José do Peixe (11,439 ha, 8.8 %); Nazaré do Piauí (599 ha, 0.4 %); São Francisco do Piauí (544 ha, 0.4 %); Flores do Piauí (315 ha, 0.3 %).
What was the weather like?
During the fire the temperature reached 38.5 °C, humidity dropped to 18 % and gusts hit 44 km/h. The fire danger index (FWI) reached 58, class Extreme.
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.
How did the fires that started in similar weather in this area end?
Fires less than 250 km away that started since 2016 with a similar FWI, humidity and dry spell: 27. Their median duration was 16 days and their median area 4,975 ha; 19 % went past 10,000 ha. Only 2 of its 27 twins burned more. The weather on the first day does not explain everything: the wind in the following days, the fuel and the firefighting also count. In 20 of 27, not even 1 mm fell in the ten days after the end: they went out without rain. In the rest, the first rainy day brought a median of 1.6 mm.

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 Changes in area, dates, name, official record or merged pages, compared every night 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
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; 2 polygons grouped in this page.
  • Dates from the perimeter: the VIIRS detections inside it did not change them. 569 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.

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.