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PT · Portugal ·

Mértola fire, September 2026 São Miguel do Pinheiro, São Pedro de Solis e São Sebastião dos Carros, Martim Longo

Out · last detection 11 Sept 2026, 13:14 UTC

The fire started on 11 September 2026 in São Miguel do Pinheiro, São Pedro de Solis e São Sebastião dos Carros, Portugal, and satellites saw it burning for 1 day. Copernicus mapped a burnt perimeter of 157 hectares from satellite imagery, spread across 2 freguesias. According to ICNF, it was detected on 11 September 2026 at 11:50 and declared extinguished on 11 September 2026.

Number 61 in Portugal in 2026, of 87.

The power measured by the satellite is low (9.0 MW in the strongest hotspot), more typical of grass or stubble burning, or a slow surface fire, than of a large crown fire.

Burnt area
157ha
Copernicus perimeter
Duration
≈ 1day
11 Sept 2026 – 11 Sept 2026
Freguesias hit
2
freguesias
Started on
11 Sept
2026
Heat detections
12
in a single hotspot: 9 MW
Danger at start
41
Very high · FWI index
Average daily power
90MW
detected power per day, on average

Where it burned

HOTSPOTS BY DAY 11 Sept11 Sept

How it evolved, day by day

11 Sept 2026 · 90 MW · 12

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

The weather it burned in

34°high
28km/h · peak gust
22%lowest humidity

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

This area had burned before

No earlier perimeters overlap this fire since 2016, when the satellite record begins.

What happened to each freguesia

  1. São Miguel do Pinheiro, São Pedro de Solis e São Sebastião dos Carros 816 inhabitants · 10.4 km from the centre where it started
    157 ha reached on 11 Sept
    0.6 %
  2. Martim Longo 928 inhabitants · 9.5 km from the centre
    0 ha
    0.0 %

Burnt area inside each freguesia, from crossing the official 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.

What burned

  • Broadleaved forest88 %
  • Scrub and transitional woodland7.0 %
  • Agricultural areas3.2 %
  • Sclerophyllous scrub1.9 %

Natura 2000 protected area affected: 19 %

Natura 2000 sites (European Environment Agency, 2024 release) crossed by the perimeter.

Land cover inside the perimeter according to Corine Land Cover, as reported by Copernicus.

People and buildings inside the perimeter

GHSL 2025
Built-up area< 0.1 ha
Residents< 20

Inside 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

Official record

According to ICNF, this fire started on 11 September 2026 and burned 158 ha (the satellite measured 157 ha).

ICNF (Instituto da Conservação da Natureza e das Florestas). This is the agency’s operational record: its figures may be revised when the year’s statistics are closed.

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 60 days without rain: 2.4 % of the area in Portugal

Day High Min. humidity Peak gust Rain Danger (FWI)
11 Sept 34.0 °C 22 % 28 km/h 0.0 mm Very high 41
12 Sept after 35.3 °C 23 % 25 km/h 0.0 mm Very high 40
13 Sept after 35.2 °C 20 % 23 km/h 0.0 mm Very high 41
14 Sept after 35.8 °C 22 % 31 km/h 0.0 mm Very high 46
15 Sept after 34.4 °C 21 % 39 km/h 0.0 mm Extreme 51
16 Sept after 28.7 °C 39 % 42 km/h 0.0 mm Very high 41
17 Sept after 30.0 °C 24 % 26 km/h 0.0 mm High 35
18 Sept after 30.5 °C 22 % 22 km/h 0.0 mm High 34
19 Sept after 32.2 °C 29 % 27 km/h 0.0 mm Very high 39
20 Sept after 32.7 °C 28 % 37 km/h 0.0 mm Very high 44

Its twins: fires that started in the same weather

It started with an FWI of 40.6, a minimum humidity of 22% and more than two months without rain. Fires in the area that started in weather like this since 2016: 22.

FWI at the start 40.6
Minimum humidity 22 %
Days without rain 60+
this fire chosen twins rest of the area
Almost identicalSimilar

Outlines of the closest twins

Odemira fire, September 2026
496 ha 2 days FWI 40.0 Min. humidity 20 % 49 km away, in 2026

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

What happened to them

1 day
median duration
298 ha
median area
23 %
went past 1,000 ha
2.4 mm
rain at the end (median; 4 of 22 had it)

It stayed below its twins: 157 ha against a median of 298 ha. It lasted 1 day, against 1 day.

In 18 of 22, 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 2.4 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
28km/h · max. gust

It was considered over on 11 Sept, and not even 1 mm fell in the following ten days: it went out without rain. Twins with rain when they ended: 4 of 22, with a median of 2.4 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 · 4 Sept 2026
After · 18 Sept 2026

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 13 September 2026 the air beside the fire reached 6 µg/m³ of PM2.5, but no daily average passed the WHO guideline (15).

PM2.5 peak6 µg/m³
Days over the guideline0 days
PM1014 µg/m³
Optical depth0.11
9 Sept11 Sept13 Sept
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 · 12Every 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 Portugal

Frequently asked questions

How long did the Mértola fire last?
The official perimeter only gives the start date (11 September 2026). The end comes from the heat detections inside the perimeter: it burned until 11 September 2026 (1 day from 11 September 2026), the last day with detections before more than 10 days in a row without any, so it is approximate. According to ICNF, it was detected on 11 September 2026 at 11:50 and declared extinguished on 11 September 2026.
How much area did it burn?
The perimeter Copernicus measured from satellite imagery is 157 hectares (1.6 km²). Official national figures may differ.
Which freguesias burned?
The fire entered 2 freguesias: São Miguel do Pinheiro, São Pedro de Solis e São Sebastião dos Carros (157 ha, 0.6 %); Martim Longo (0 ha, 0.0 %).
Did the fire reach a town?
The fire came within 9.5 km of the centre of Martim Longo, the closest of the areas it touched. That is the distance from the perimeter, or the nearest hotspot, to the point marking the centre; it does not mean it entered the houses.
What was the weather like?
During the fire the temperature reached 34.0 °C, humidity dropped to 22 % and gusts hit 28 km/h. The fire danger index (FWI) reached 41, class Very high.
Where does this data come from?
From the EFFIS (Copernicus) burnt perimeter, NASA FIRMS VIIRS hotspots and the administrative boundaries of Portugal (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: 22. Their median duration was 1 day and their median area 298 ha; 23 % went past 1,000 ha. In 18 of 22, 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 2.4 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: 112 · 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 112.

How we know this
  • Perimeter: EFFIS (Copernicus), mapped on satellite imagery.
  • The official perimeter has no end date: the end is the last day with VIIRS detections inside the perimeter before a gap of more than 10 days (150 days at most), so it is approximate. 12 Suomi-NPP VIIRS detections on those dates.
  • Compared with ICNF: 158 official ha against 157 ha of perimeter; they agree within 25%.
  • 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 and land cover come from the Copernicus European Forest Fire Information System (EFFIS), measured on MODIS and Sentinel-2 imagery and published under CC BY 4.0. Heat detections come from the VIIRS sensors aboard Suomi-NPP and NOAA-20, distributed by NASA FIRMS at 375 m resolution. Freguesia boundaries come from geoBoundaries ADM3 (CC0 1.0 Universal (CC0 1.0) Public Domain Dedication). The area per freguesia is computed by WorldFires by crossing the perimeter with those boundaries, so it may differ slightly from each country’s official figure.