Arcos de Valdevez fire, 4 September 2024
São Jorge e Ermelo, Vale, Soajo
Out · last detection 5 Sept 2024, 01:40 UTC
The fire started on 4 September 2024 in São Jorge e Ermelo, Portugal, and satellites saw it burning for 2 days. Copernicus mapped a burnt perimeter of 1,218 hectares from satellite imagery, spread across 3 freguesias. According to ICNF, the largest of the 2 recorded fires was detected on 3 September 2024 at 20:21 and declared extinguished on 5 September 2024.
It is the 3th largest in Arcos de Valdevez since 2016 (of 29 with a page). Number 18 in Portugal in 2024, of 69.
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
24.9°C · 40% RH
High of 24.9 °C and minimum humidity of 40% on 4 September 2024; gusts of 43 km/h on 5 September 2024.
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.
Show
· reconstructedofficial
Matched with the official ICNF record
Matches: 1,245 ha in the official record (records: 2).
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
Fire radiative power detected each day, in megawatts, and number of hotspots. The magenta bar marks the peak day.
The weather it burned in
25°high
43km/h · peak gust
40%lowest humidity
It had gone 3 days without rain (1 mm or more) when it started. Rain came after the fire: 3.7 mm on 6 Sept.
This area had burned before
98% of the perimeter overlaps earlier fires recorded since 2016: 1,194 ha in 2016, 9 ha in 2018, 11 ha in 2020, 85 ha in 2021, 335 ha in 2022, 44 ha in 2023. Part of it burned more than once, so the yearly figures add up to more than the 1,194 ha that had burned before.
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.
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< 0.1ha
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.
According to ICNF, 2 fires started inside this perimeter on these dates, totalling 1,245 ha (the satellite measured 1,218 ha).
ICNF records each fire that started at a different time or place separately; the satellite sees a single burned area, so this page groups them together. The numbers on the map show where each one started.
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)
4 Sept
24.9 °C
40 %
42 km/h
0.0 mm
High 30
5 Sept
20.1 °C
46 %
43 km/h
0.0 mm
High 27
6 Sept after
16.2 °C
74 %
44 km/h
3.7 mm
Moderate 20
Its twins: fires that started in the same weather
It started with an FWI of 29.8, a minimum humidity of 40% and 3 days without rain. Fires in the area that started in weather like this since 2016: 19.
FWI at the start29.8
Minimum humidity40 %
Days without rain3
this firechosen twinsrest of the area
Almost identicalSimilar
Outlines of the closest twins
This fire · Arcos de Valdevez fire, 4 September 2024
1,218 ha2 daysFWI 29.8Min. humidity 40 %
Cabeceiras de Basto fire, August 2022
120 ha1 dayFWI 29.9Min. humidity 39 %44 km away, in 2022
First rain (1 mm or more) after it ended: 12.3 mm on 5 Sept.
It was 6.3 times larger than the median of its twins and lasted 2 days, against 2 days.
Only 2 of its 19 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 12 of 19, 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 12.3 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
3.7 mmfirst rain
6 Septthe day after it ended
43km/h · max. gust
It was considered over on 5 Sept, and on 6 Sept 3.7 mm fell. We do not know whether the rain or the firefighters put it out. Twins with rain when they ended: 7 of 19, with a median of 12.3 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 · 28 Aug 2024
After · 12 Sept 2024
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 6 September 2024 the air beside the fire reached 24 µg/m³ of PM2.5, but no daily average passed the WHO guideline (15).
PM2.5 peak24µg/m³
Days over the guideline0days
PM1032µg/m³
Optical depth0.28
WHO 15
2 Sept4 Sept6 Sept8 Sept
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· 92Every 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.
Copernicus dates it between 4 September 2024 and 5 September 2024: 2 days between the first and last image with fire. According to ICNF, the largest of the 2 recorded fires was detected on 3 September 2024 at 20:21 and declared extinguished on 5 September 2024.
How much area did it burn?
The perimeter Copernicus measured from satellite imagery is 1,218 hectares (12.2 km²). Official national figures may differ.
Which freguesias burned?
The fire entered 3 freguesias: São Jorge e Ermelo (930 ha, 38 %); Vale (280 ha, 19 %); Soajo (9 ha, 0.2 %).
Did the fire reach a town?
The fire started in São Jorge e Ermelo and reached its centre: the point marking it was inside the burnt area or less than 500 metres from it. That does not mean houses burned.
What was the weather like?
During the fire the temperature reached 24.9 °C, humidity dropped to 40 % and gusts hit 43 km/h. The fire danger index (FWI) reached 30, class 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: 19. Their median duration was 2 days and their median area 192 ha; 11 % went past 1,000 ha. Only 2 of its 19 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 12 of 19, 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 12.3 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›
Perimeter: EFFIS (Copernicus), mapped on satellite imagery.
Dates from the perimeter: the VIIRS detections inside it did not change them. 92 Suomi-NPP VIIRS detections on those dates.
Compared with ICNF: 1,245 official ha against 1,218 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.
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.