The fire started on 31 March 2021 in Piloña, Spain, and satellites saw it burning for 1 day. Copernicus mapped a burnt perimeter of 131 hectares from satellite imagery, spread across a single municipality.
It is the 145th largest in Asturias since 2016 (of 225 with a page). Number 96 in Spain in 2021, of 120.
The power measured by the satellite is low (5.6 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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Tick the figures you want: they make up the lede and the CSV.
Burned area
with caveats
131ha
Perimeter published by EFFIS (Copernicus).
This page131EGIF (MITECO)183
Source
EFFIS (Copernicus)
Date
perimeter revised on 26 January 2022
+− cross-check
EGIF (MITECO): 183 ha (matched records: 2). Difference between the page and the official record: −28.3%. Matched on 8 November 2026. The two figures differ a lot, so these may not be exactly the same fire: take them as nearby records.
Duration by satellite
satellite only
1day
31 Mar 2021 to 31 Mar 2021: first and last day with fire on the page.
Source
EFFIS (Copernicus) · NASA FIRMS · VIIRS
Date
last detection: 31 Mar 2021, 13:16 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
31 Mar 2021
First day with fire seen by the satellites or the perimeter.
Source
EFFIS (Copernicus) · NASA FIRMS · VIIRS
Date
31 Mar 2021
+− cross-check
The two figures differ a lot, so these may not be exactly the same fire: take them as nearby records.
Hotspots
satellite only
3
VIIRS detections at 375 m. Most intense hotspot: 6 MW.
Source
NASA FIRMS · VIIRS (Suomi NPP)
Date
31 Mar 2021 – 31 Mar 2021
+− 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
16MW
Total radiative power on 31 March 2021; hotspots that day: 3.
Source
NASA FIRMS · VIIRS (FRP)
Date
31 Mar 2021
+− 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
7.5FWI · low
Fire Weather Index (Canadian system) computed by WorldFires for the day the fire started. Consecutive days without rain before: 4.
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
23.2°C · 30% RH
High of 23.2 °C and minimum humidity of 30% on 31 March 2021; gusts of 35 km/h on 31 March 2021.
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 EGIF (MITECO) record
Nearby records with very different figures: 183 ha (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
23°high
35km/h · peak gust
30%lowest humidity
It had gone 4 days without rain (1 mm or more) when it started. Rain came after the fire: 5.5 mm on 2 Apr.
This area had burned before
No earlier perimeters overlap this fire since 2016, when the satellite record begins.
What happened to each town
Piloña6,716 inhabitants · 3.1 km from the centrewhere it started
131 hareached on 31 Mar
0.5 %
Burnt area inside each municipality, 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
Other natural land98 %
Scrub and transitional woodland2.3 %
Land cover inside the perimeter according to Corine Land Cover, as reported by Copernicus.
Official record
Several official records match this area
According to EGIF (MITECO), 2 fires started inside this perimeter on these dates, totalling 183 ha (the satellite measured 131 ha). The two figures differ a lot, so these may not be exactly the same fire: take them as nearby records.
EGIF (MITECO) 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)
31 Mar
23.2 °C
30 %
35 km/h
0.0 mm
Low 8
1 Apr after
17.5 °C
49 %
40 km/h
0.8 mm
Low 7
2 Apr after
14.7 °C
76 %
35 km/h
5.5 mm
Very low 0
Its twins: fires that started in the same weather
It started with an FWI of 7.5, a minimum humidity of 30% and 4 days without rain. Fires in the area that started in weather like this since 2016: 48.
FWI at the start7.5
Minimum humidity30 %
Days without rain4
this firechosen twinsrest of the area
Almost identicalSimilar
Outlines of the closest twins
This fire · Piloña fire, 31 March 2021
131 ha1 dayFWI 7.5Min. humidity 30 %
Piloña fire, March 2023
509 ha3 daysFWI 9.3Min. humidity 30 %9 km away, in 2023
First rain (1 mm or more) after it ended: 6.9 mm on 1 Apr.
It stayed below its twins: 131 ha against a median of 222 ha. It lasted 1 day, against 2 days.
In 1 of 48, 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 4.6 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
5.5 mmfirst rain
2 Apr2 days after it ended
35km/h · max. gust
It was considered over on 31 Mar, and on 2 Apr 5.5 mm fell. We do not know whether the rain or the firefighters put it out. Twins with rain when they ended: 47 of 48, with a median of 4.6 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 · 24 Mar 2021
After · 7 Apr 2021
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 1 April 2021 the air beside the fire reached 66 µg/m³ of PM2.5. That day averaged 43: 2.8 times the WHO daily guideline (15).
PM2.5 peak66µg/m³
Days over the guideline5days
PM1089µg/m³
WHO 15
29 Mar31 Mar2 Apr
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· 3Every 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 31 March 2021 and 31 March 2021: 1 day between the first and last image with fire.
How much area did it burn?
The perimeter Copernicus measured from satellite imagery is 131 hectares (1.3 km²). Official national figures may differ.
Which municipalities burned?
The fire only entered Piloña (131 ha, 0.5 %).
Did the fire reach a town?
The fire started in Piloña and came within 3.1 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 23.2 °C, humidity dropped to 30 % and gusts hit 35 km/h. The fire danger index (FWI) reached 8, class Low.
Where does this data come from?
From the EFFIS (Copernicus) burnt perimeter, NASA FIRMS VIIRS hotspots and the administrative boundaries of Spain (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: 48. Their median duration was 2 days and their median area 222 ha; 6 % went past 1,000 ha. In 1 of 48, 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 4.6 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. 3 Suomi-NPP VIIRS detections on those dates.
Compared with EGIF (MITECO): 183 official ha against 131 ha of perimeter; similar, but with reservations.
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. Municipal boundaries come from geoBoundaries ADM3 (Creative Commons Attribution 4.0 International (CC BY 4.0)). The area per municipality is computed by WorldFires by crossing the perimeter with those boundaries, so it may differ slightly from each country’s official figure.