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PT · Portugal · –

Alcaria fire, September 2026 Portugal

Out · last detection 3 Oct 2026, 13:23 UTC

Satellites first detected fire on 22 September 2026 in Alcaria, Portugal. It was active for 12 days, with 4 heat detections and an area with fire of about 154 hectares rebuilt from them, spread across a single freguesia.

The power measured by the satellite is low (6.8 MW in the strongest hotspot), more typical of grass or stubble burning, or a slow surface fire, than of a large crown fire.

Copernicus has not yet published the burnt perimeter, which takes a few days to measure on satellite imagery. For now the area is the one rebuilt from heat detections (about 14 hectares per pixel). When the perimeter arrives, this page picks it up on its own and keeps the same address.

Area with fire
≈ 154ha
rebuilt from hotspots, no official perimeter yet
Duration
12days
22 Sept 2026 – 3 Oct 2026
Freguesias hit
0
freguesias
Started on
22 Sept
2026
Heat detections
4
in a single hotspot: 7 MW
Danger at start
36
High · FWI index
Average daily power
20MW
detected power per day, on average

Where it burned

HOTSPOTS BY DAY 22 Sept3 Oct
3 Oct 2026

How it evolved, day by day

22 Sept 2026 · 0 MW · 0 25 Sept 2026 · 0 MW · 0 2 Oct 2026 · 20 MW · 4 3 Oct 2026 · 0 MW · 0
22 Sept 25 Sept 2 Oct 3 Oct

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
51km/h · peak gust
11%lowest humidity

It had gone 25 days without rain (1 mm or more) when it started. Rain came after the fire: 2.3 mm on 4 Oct.

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 Very dry air: 4.7 % of the area in Portugal

Day High Min. humidity Peak gust Rain Danger (FWI)
22 Sept 34.5 °C 13 % 23 km/h 0.0 mm High 36
23 Sept 34.3 °C 17 % 18 km/h 0.0 mm High 36
24 Sept 33.8 °C 17 % 39 km/h 0.0 mm Very high 44
25 Sept 32.0 °C 14 % 23 km/h 0.0 mm Very high 38
26 Sept 30.5 °C 11 % 22 km/h 0.0 mm High 38
27 Sept 29.1 °C 20 % 24 km/h 0.0 mm High 37
28 Sept 23.3 °C 47 % 32 km/h 1.5 mm Moderate 12
29 Sept 22.8 °C 46 % 51 km/h 4.6 mm Low 7
30 Sept 20.0 °C 50 % 39 km/h 4.5 mm Very low 3
1 Oct 21.5 °C 46 % 29 km/h 0.0 mm Low 6
2 Oct 24.9 °C 47 % 26 km/h 0.7 mm Low 9
3 Oct 22.6 °C 63 % 25 km/h 2.4 mm Very low 3
4 Oct after 22.3 °C 57 % 28 km/h 2.3 mm Very low 3

Its twins: fires that started in the same weather

It started with an FWI of 36.4, a minimum humidity of 13% and 25 days without rain. Fires in the area that started in weather like this since 2016: 22.

FWI at the start 36.4
Minimum humidity 13 %
Days without rain 25
this fire chosen twins rest of the area
Almost identicalSimilar

Outlines of the closest twins

Aboadela, Sanche e Várzea fire, October 2017
311 ha 5 days FWI 34.4 Min. humidity 13 % 125 km away, in 2017

First rain (1 mm or more) after it ended: 1.1 mm on 16 Oct.

What happened to them

4 days
median duration
1,089 ha
median area
50 %
went past 1,000 ha
3.0 mm
rain at the end (median; 16 of 22 had it)

It stayed below its twins: 154 ha against a median of 1,089 ha. It lasted 12 days, against 4 days.

In 6 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 3.0 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

2.3 mmfirst rain
4 Octthe day after it ended
51km/h · max. gust

It was considered over on 3 Oct, and on 4 Oct 2.3 mm fell. We do not know whether the rain or the firefighters put it out. Twins with rain when they ended: 16 of 22, with a median of 3.0 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 · 15 Sept 2026
After · 10 Oct 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 27 September 2026 the air beside the fire reached 16 µg/m³ of PM2.5, but no daily average passed the WHO guideline (15).

PM2.5 peak16 µg/m³
Days over the guideline0 days
PM1036 µg/m³
Optical depth0.35
20 Sept23 Sept26 Sept29 Sept2 Oct
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 · 4Every 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 Alcaria fire last?
According to the heat detections seen by satellite, it burned from 22 September 2026 to 3 October 2026 (12 days between the first and the last detection). There is no perimeter yet to date it.
How much area did it burn?
There is no official perimeter yet. Heat detections rebuild about 154 hectares with fire (1.5 km²); Copernicus will publish the measured figure within days.
What was the weather like?
During the fire the temperature reached 34.5 °C, humidity dropped to 11 % and gusts hit 51 km/h. The fire danger index (FWI) reached 44, 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 4 days and their median area 1,089 ha; 50 % went past 1,000 ha. In 6 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 3.0 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
  • No perimeter yet: the area (≈ 154 ha) is estimated by counting VIIRS pixels with fire, about 14 ha each.
  • Dates of the first and last VIIRS detection of the cluster. 4 Suomi-NPP VIIRS detections on those dates.
  • Weather: Copernicus ERA5 reanalysis at the fire location, in cells of about 25 km.

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.