Santo Tirso fire, September 2026
Água Longa, Lamelas e Guimarei, Agrela
Out · last detection 23 Sept 2026, 03:28 UTC
The fire started on 22 September 2026 in Água Longa, Portugal, and satellites saw it burning for 2 days. Copernicus mapped a burnt perimeter of 291 hectares from satellite imagery, spread across 5 freguesias. According to ICNF, it was detected on 22 September 2026 at 15:08 and declared extinguished on 23 September 2026.
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
31.0°C · 34% RH
High of 31.0 °C and minimum humidity of 34% on 22 September 2026; gusts of 23 km/h on 23 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.
Show
· reconstructedofficial
Matched with the official ICNF record
Matches: 286 ha in the official record (records: 1).
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
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 forest55 %
Scrub and transitional woodland41 %
Artificial surfaces3.4 %
Land cover inside the perimeter according to Corine Land Cover, as reported by Copernicus.
People and buildings inside the perimeter
GHSL 2025
Built-up area2.2ha
Residents< 20
Inside the perimeter there were about 2.2 hectares of 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.
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)
22 Sept
31.0 °C
34 %
23 km/h
0.0 mm
Moderate 18
23 Sept
29.2 °C
44 %
23 km/h
0.0 mm
Moderate 14
24 Sept after
22.7 °C
66 %
24 km/h
0.0 mm
Moderate 13
25 Sept after
23.2 °C
57 %
30 km/h
0.0 mm
Moderate 14
26 Sept after
25.2 °C
50 %
18 km/h
0.0 mm
Low 10
27 Sept after
22.6 °C
63 %
30 km/h
0.0 mm
Moderate 16
28 Sept after
22.3 °C
66 %
29 km/h
0.1 mm
Moderate 13
29 Sept after
24.2 °C
58 %
65 km/h
19.8 mm
High 25
Its twins: fires that started in the same weather
It started with an FWI of 17.6, a minimum humidity of 34% and 13 days without rain. Fires in the area that started in weather like this since 2016: 19.
FWI at the start17.6
Minimum humidity34 %
Days without rain13
this firechosen twinsrest of the area
Almost identicalSimilar
Outlines of the closest twins
This fire · Santo Tirso fire, September 2026
291 ha2 daysFWI 17.6Min. humidity 34 %
Lobeira fire, September 2019
159 ha2 daysFWI 18.8Min. humidity 34 %90 km away, in 2019
First rain (1 mm or more) after it ended: 6.0 mm on 16 Sept.
It burned an area similar to its twins (291 ha against a median of 252 ha) and lasted 2 days, against 2 days.
In 4 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 15.1 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
19.8 mmfirst rain
29 Sept6 days after it ended
23km/h · max. gust
It was considered over on 23 Sept, and on 29 Sept 19.8 mm fell. We do not know whether the rain or the firefighters put it out. Twins with rain when they ended: 15 of 19, with a median of 15.1 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 · 30 Sept 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 19 September 2026 the air beside the fire reached 18 µg/m³ of PM2.5, but no daily average passed the WHO guideline (15).
PM2.5 peak18µg/m³
Days over the guideline0days
PM1022µg/m³
Optical depth0.18
WHO 15
1819202122
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· 7Every 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.
The official perimeter only gives the start date (22 September 2026). The end comes from the heat detections inside the perimeter: it burned until 23 September 2026 (2 days from 22 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 22 September 2026 at 15:08 and declared extinguished on 23 September 2026.
How much area did it burn?
The perimeter Copernicus measured from satellite imagery is 291 hectares (2.9 km²). Official national figures may differ.
Which freguesias burned?
The fire entered 5 freguesias: Água Longa (221 ha, 17 %); Lamelas e Guimarei (47 ha, 3.8 %); Agrela (23 ha, 3.3 %); Folgosa (1 ha, 0.1 %); Covelas (0 ha, 0.0 %).
Did the fire reach a town?
The fire started in Água Longa and came within 0.9 km of its centre. 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 31.0 °C, humidity dropped to 34 % and gusts hit 23 km/h. The fire danger index (FWI) reached 18, class Moderate.
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 252 ha; 11 % went past 1,000 ha. In 4 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 15.1 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.
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. 7 Suomi-NPP VIIRS detections on those dates.
Compared with ICNF: 286 official ha against 291 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.