How long did the Arcos de Valdevez fire last?

The official perimeter only gives the start date (18 August 2026). The end comes from the heat detections inside the perimeter: it burned until 19 August 2026 (6 days from 14 August 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 18 August 2026 at 15:40 and declared extinguished on 19 August 2026.

How much area did it burn?

The perimeter Copernicus measured from satellite imagery is 164 hectares (1.6 km²). Official national figures may differ.

Which municipalities burned?

The fire entered 3 municipalities: Rio Frio (146 ha, 7.6 %); Padreiro (Salvador e Santa Cristina) (18 ha, 4.3 %); Miranda (0 ha, 0.0 %).

Did the fire reach a town?

The fire came within 0.6 km of the centre of Miranda, the closest of the areas it touched. 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 33.2 °C, humidity dropped to 34 % and gusts hit 35 km/h. The fire danger index (FWI) reached 24, 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.

PT · Portugal · 2026-08-14 → 2026-08-19

Arcos de Valdevez fire, August 2026 Rio Frio, Padreiro (Salvador e Santa Cristina), Miranda

Out · last detection 19 Aug 2026, 02:24 UTC

The fire started on 14 August 2026 in Rio Frio, Portugal, and satellites saw it burning for 6 days. Copernicus mapped a burnt perimeter of 164 hectares from satellite imagery, spread across 3 municipalities. According to ICNF, it was detected on 18 August 2026 at 15:40 and declared extinguished on 19 August 2026.

It is the 18th largest in Arcos de Valdevez since 2016 (of 29 with a page). Number 57 in Portugal in 2026, of 87.

The power measured by the satellite is low (2.8 MW in the strongest hotspot), more typical of grass or stubble burning, or a slow surface fire, than of a large crown fire.

Compare with…

Suggestions: Arcos de Valdevez · 2016 Cabração e Moreira do Lima · 2016 Ponte da Barca · 2025 Monção · 2017

Burnt area: 164ha; Copernicus perimeter
Duration: ≈ 6days; 14 Aug 2026 – 19 Aug 2026
Municipalities hit: 3; freguesias
Started on: 14 Aug; 2026
Heat detections: 7; in a single hotspot: 3 MW
Danger at start: 15; Moderate · FWI index
Average daily power: 8MW; detected power per day, on average

HOTSPOTS BY DAY 14 Aug19 Aug

Play back 19 Aug 2026

How it evolved, day by day

18 Aug 19 Aug

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

The weather it burned in

33°high

35km/h · peak gust

34%lowest humidity

It had gone 9 days without rain (1 mm or more) when it started. Rain came after the fire: 17.0 mm on 23 Aug.

This area had burned before

No earlier perimeters overlap this fire since 2016, when the satellite record begins.

What happened to each town

Rio Frio 536 inhabitants · 0.8 km from the centre where it started

146 ha reached on 18 Aug

7.6 %
Padreiro (Salvador e Santa Cristina) 349 inhabitants · 0.8 km from the centre

18 ha

4.3 %
Miranda 245 inhabitants · 0.6 km from the centre

0 ha

0.0 %

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

Scrub and transitional woodland43 %
Mixed forest34 %
Agricultural areas20 %
Other natural land2.5 %
Broadleaved forest0.6 %

Land cover inside the perimeter according to Corine Land Cover, as reported by Copernicus.

Official record

According to ICNF, this fire started on 18 August 2026 and burned 149 ha (the satellite measured 164 ha).

Arcos de Valdevez Padreiro (Santa Cristina) 18 August 2026 · 15:40 149 ha · extinguished on 19 August 2026 · cause: rekindling

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)
14 Aug	27.0 °C	61 %	34 km/h	0.0 mm	Moderate 15
15 Aug	29.5 °C	49 %	34 km/h	0.5 mm	Moderate 16
16 Aug	30.7 °C	36 %	26 km/h	0.0 mm	Moderate 20
17 Aug	33.0 °C	34 %	26 km/h	0.0 mm	High 23
18 Aug	33.2 °C	35 %	35 km/h	0.0 mm	High 24
19 Aug	26.2 °C	57 %	28 km/h	0.0 mm	Moderate 17
20 Aug after	22.2 °C	65 %	41 km/h	0.8 mm	Moderate 12
21 Aug after	23.4 °C	42 %	41 km/h	0.0 mm	Moderate 18
22 Aug after	23.7 °C	51 %	33 km/h	0.0 mm	Moderate 17
23 Aug after	24.4 °C	48 %	38 km/h	17.0 mm	Very low 2

Before and after, from space

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

↔

Before · 7 Aug 2026

After · 26 Aug 2026

Before After

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 20 August 2026 the air beside the fire reached 131 µg/m³ of PM2.5. That day averaged 47: 3.1 times the WHO daily guideline (15).

PM2.5 peak131 µg/m³

Days over the guideline3 days

PM10192 µg/m³

Optical depth0.67

WHO 15

161718192021222324

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 · 7Every 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 time	Satellite	FRP (MW)	Lat	Lon

Other fires nearby

All fires in Portugal ›

Frequently asked questions

How long did the Arcos de Valdevez fire last?: The official perimeter only gives the start date (18 August 2026). The end comes from the heat detections inside the perimeter: it burned until 19 August 2026 (6 days from 14 August 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 18 August 2026 at 15:40 and declared extinguished on 19 August 2026.
How much area did it burn?: The perimeter Copernicus measured from satellite imagery is 164 hectares (1.6 km²). Official national figures may differ.
Which municipalities burned?: The fire entered 3 municipalities: Rio Frio (146 ha, 7.6 %); Padreiro (Salvador e Santa Cristina) (18 ha, 4.3 %); Miranda (0 ha, 0.0 %).
Did the fire reach a town?: The fire came within 0.6 km of the centre of Miranda, the closest of the areas it touched. 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 33.2 °C, humidity dropped to 34 % and gusts hit 35 km/h. The fire danger index (FWI) reached 24, 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.

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 · Emergency number and official warnings ›

Satellite cross-check

NASA FIRMS ↗
EFFIS · Copernicus ↗

History of this page Changes in area, dates, name, official record or merged pages, compared every night since 24 October 2026.

No changes since 24 October 2026.

RSS Changes to this page

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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.

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How 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: 149 official ha against 164 ha of perimeter; they agree within 25%.
Weather: Copernicus ERA5 reanalysis at the fire location, in cells of about 25 km.

How we build fire pages: methodology ›

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.

Where it burned