Skip to content
worldfires
PT · Portugal · →

Arouca fire, January 2021 Alvarenga, Cabril

Out · last detection 14 Jan 2021, 13:40 UTC

The fire started on 11 January 2021 in Alvarenga, Portugal, and satellites saw it burning for 4 days. Copernicus mapped a burnt perimeter of 206 hectares from satellite imagery, spread across 2 municipalities.

Number 12 in Portugal in 2021, of 30.

The power measured by the satellite is low (21.2 MW in the strongest hotspot), more typical of grass or stubble burning, or a slow surface fire, than of a large crown fire.

Burnt area
206ha
Copernicus perimeter
Duration
4days
11 Jan 2021 – 14 Jan 2021
Municipalities hit
2
freguesias
Started on
11 Jan
2021
Heat detections
4
in a single hotspot: 21 MW
Danger at start
1
Very low · FWI index
Energy released
42MW
sum of detected power

Where it burned

14 Jan 2021
HOTSPOTS BY DAY 11 Jan14 Jan

How it evolved, day by day

1114

Fire radiative power detected each day, in megawatts, and number of hotspots. The magenta bar marks the peak day.

The weather it burned in

8°high
43km/h · peak gust
48%lowest humidity

It had gone 10 days without rain (1 mm or more) when it started. Rain came after the fire: 33.7 mm on 20 Jan.

This area had burned before

52% of the perimeter overlaps earlier fires recorded since 2016: 34 ha in 2016, 74 ha in 2017.

What happened to each town

  1. Alvarenga 1,057 inhabitants · 4.7 km from the town
    165 ha reached on 11 Jan
    4.2 %
  2. Cabril 1.5 km from the town where it started
    42 ha reached on 11 Jan
    1.9 %

Burnt area inside each municipality, from crossing the official perimeter with administrative boundaries. The distance is from the town centre to the nearest fire: staying a kilometre away does not mean it reached the houses.

What burned

  • Other natural land79 %
  • Scrub and transitional woodland18 %
  • Agricultural areas3.9 %

Natura 2000 protected area affected: 100 %

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.

Official record

According to ICNF, this fire started on 8 January 2021 and burned 155 ha (the satellite measured 206 ha). The two figures differ a lot, so these may not be exactly the same fire: take them as nearby records.

ICNF (Instituto da Conservação da Natureza e das Florestas). This is the agency’s operational record: its figures may be revised when the year’s statistics are closed.

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)

Day High Min. humidity Peak gust Rain Danger (FWI)
11 Jan 4.7 °C 48 % 43 km/h 0.0 mm Very low 1
12 Jan 6.8 °C 49 % 22 km/h 0.0 mm Very low 1
13 Jan 7.6 °C 54 % 18 km/h 0.0 mm Very low 1
14 Jan 7.7 °C 54 % 19 km/h 0.0 mm Very low 1
15 Jan after 7.6 °C 65 % 20 km/h 0.0 mm Very low 1
16 Jan after 7.9 °C 57 % 25 km/h 0.0 mm Very low 1
17 Jan after 8.1 °C 53 % 23 km/h 0.0 mm Very low 1
18 Jan after 10.4 °C 56 % 25 km/h 0.0 mm Very low 1
19 Jan after 7.5 °C 68 % 55 km/h 0.0 mm Very low 1
20 Jan after 8.2 °C 82 % 86 km/h 33.7 mm Very low 0

Before and after, from space

Drag the line to compare the same ground before the fire and after it.

Before · 4 Jan 2021
After · 21 Jan 2021

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 17 January 2021 the air beside the fire reached 40 µg/m³ of PM2.5. That day averaged 24: 1.6 times the WHO daily guideline (15).

PM2.5 peak40 µg/m³
Days over the guideline5 days
PM1045 µg/m³
91011121314151617
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 Arouca fire last?
Copernicus dates it between 11 January 2021 and 14 January 2021: 4 days between the first and last image with fire.
How much area did it burn?
The perimeter Copernicus measured from satellite imagery is 206 hectares (2.1 km²). Official national figures may differ.
Which municipalities burned?
The fire entered 2 municipalities: Alvarenga (165 ha, 4.2 %); Cabril (42 ha, 1.9 %).
Did the fire reach a town?
The closest fire to a town centre came within 1.5 km of Cabril. That is the distance to the perimeter or nearest hotspot; it does not mean it entered the houses.
What was the weather like?
During the fire the temperature reached 7.7 °C, humidity dropped to 48 % and gusts hit 43 km/h. The fire danger index (FWI) reached 1, class Very low.
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.

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

Satellite cross-check

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.

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. Municipal boundaries come from geoBoundaries ADM3 (CC0 1.0 Universal (CC0 1.0) Public Domain Dedication). 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.