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.
matches the official recordwith caveatssatellite onlymodel
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Burned area
satellite only
≈ 154ha
Estimated from hotspots: no perimeter has been published yet.
Source
NASA FIRMS · VIIRS
Date
22 Sept 2026 – 3 Oct 2026
+− cross-check
This is an estimate from the VIIRS pixels that saw fire. It will change when the perimeter is published.
Duration by satellite
satellite only
12days
22 Sept 2026 to 3 Oct 2026: first and last day with fire on the page.
Source
NASA FIRMS · VIIRS
Date
last detection: 3 Oct 2026, 13:23 UTC
+− cross-check
Satellites pass a few times a day and cloud or smoke can hide the fire: a lack of detections is not an official extinction. Each country’s emergency service declares a fire contained or out.
Start
satellite only
22 Sept 2026
First day with fire seen by the satellites or the perimeter.
Source
NASA FIRMS · VIIRS
Date
22 Sept 2026
+− cross-check
No official record is matched to this page, so the alert time and the cause are not known here.
Hotspots
satellite only
4
VIIRS detections at 375 m. Most intense hotspot: 7 MW.
Source
NASA FIRMS · VIIRS (Suomi NPP)
Date
22 Sept 2026 – 3 Oct 2026
+− cross-check
There is no official record to compare with. Each hotspot is a pixel detected in one satellite pass, not a separate fire.
The worst day
satellite only
20MW
Total radiative power on 2 October 2026; hotspots that day: 4.
Source
NASA FIRMS · VIIRS (FRP)
Date
2 Oct 2026
+− cross-check
Fire radiative power (FRP) measures the energy the fire gives off when the satellite passes. Added up by day, it compares intensity, not area.
Danger at the start
model
36.4FWI · high
Fire Weather Index (Canadian system) computed by WorldFires for the day the fire started. Consecutive days without rain before: 25.
This is an index computed from weather model data, not a measurement of the fire nor an official warning. Danger warnings are issued by each country’s authority. Emergency number and official warnings ›
Weather during the fire
model
34.5°C · 13% RH
High of 34.5 °C and minimum humidity of 13% on 22 September 2026; gusts of 51 km/h on 29 September 2026.
These are model values for a cell of about 25 km, not from a weather station: they may differ from what was measured on the ground.
ⓘThis page’s change log has been kept since 24 October 2026: every night what it publishes is compared and the difference is logged. Anything earlier is reconstructed from each source’s date and marked as reconstructed.
A version keeps the area, dates, name and official record; the area as it was logged (changes under 2% are not logged). The map, hotspots and weather always show today’s data.
Citation
A lede of about 60 words figures only, no adjectives
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
Play back3 Oct 2026
How it evolved, day by day
22 Sept25 Sept2 Oct3 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)
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 start36.4
Minimum humidity13 %
Days without rain25
this firechosen twinsrest of the area
Almost identicalSimilar
Outlines of the closest twins
Aboadela, Sanche e Várzea fire, October 2017
311 ha5 daysFWI 34.4Min. humidity 13 %125 km away, in 2017
First rain (1 mm or more) after it ended: 1.1 mm on 16 Oct.
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.
Drag the line to compare the same ground before the fire and after it.
↔
Before · 15 Sept 2026
After · 10 Oct 2026
Sentinel-2 did not pass over on that day. Try another date, or use false colour, which is daily.
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 peak16µg/m³
Days over the guideline0days
PM1036µg/m³
Optical depth0.35
WHO 15
20 Sept23 Sept26 Sept29 Sept2 Oct
GoodFairModeratePoorVery poorExtremely 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 CSVTimes in UTC. Each detection is a 375 m pixel: a large fire yields hundreds per pass.
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.
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 errorHow 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.
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.