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Viengthong fire, 2 April 2026 Viengthong, Bolikhanh

Out · last detection 18 Apr 2026, 06:56 UTC

The fire started on 2 April 2026 in Viengthong, Laos, and satellites saw it burning for 16 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 11,863 hectares from heat detections, spread across 2 municipalities.

It is the 4th largest in Bolikhamsai since 2016 (of 50 with a page). Number 31 in Laos in 2026, of 308.

Compare with…

Suggestions: Bolikhanh · 2026Bolikhanh · 2026Viengthong · 2026Viengthong · 2026

Burnt area
11,863ha
GWIS perimeter (Copernicus)
Duration
16days
2 Apr 2026 – 17 Apr 2026
Municipalities hit
2
districts
Started on
2 Apr
2026
Heat detections
455
in a single hotspot: 0 MW
Danger at start
22
High · FWI index
Average daily power
144MW
detected power per day, on average

Where it burned

HOTSPOTS BY DAY 2 Apr17 Apr
18 Apr 2026

How it evolved, day by day

2 Apr 2026 · 135 MW · 6 3 Apr 2026 · 215 MW · 12 4 Apr 2026 · 7 MW · 4 5 Apr 2026 · 96 MW · 9 6 Apr 2026 · 33 MW · 3 7 Apr 2026 · 109 MW · 20 8 Apr 2026 · 137 MW · 13 9 Apr 2026 · 378 MW · 65 10 Apr 2026 · 360 MW · 68 11 Apr 2026 · 158 MW · 38 12 Apr 2026 · 184 MW · 41 13 Apr 2026 · 117 MW · 26 14 Apr 2026 · 250 MW · 61 15 Apr 2026 · 133 MW · 58 16 Apr 2026 · 84 MW · 24 17 Apr 2026 · 24 MW · 5 18 Apr 2026 · 26 MW · 2
2 Apr 5 Apr 8 Apr 9 Apr 11 Apr 14 Apr 17 Apr

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

The weather it burned in

34°high
47km/h · peak gust
28%lowest humidity

It had gone 31 days without rain (1 mm or more) when it started. Rain came after the fire: 4.6 mm on 19 Apr.

This area had burned before

14% of the perimeter overlaps earlier fires recorded since 2016: 349 ha in 2017, 813 ha in 2019, 130 ha in 2020, 1,837 ha in 2023, 430 ha in 2024. Part of it burned more than once, so the yearly figures add up to more than the 1,708 ha that had burned before.

How big is it?

10 km
It burned the equivalent of 7.5% of the area of London (119 km² against 1,583 km²).

London boundary: geoBoundaries · Office for National Statistics (Open Government Licence v3.0).

This compares size, not location: both shapes are at the same scale, north up, centred on each other.

What happened to each town

  1. Viengthong where it started
    9,088 ha
    2.3 %
  2. Bolikhanh
    2,834 ha
    1.1 %

Burnt area inside each municipality, from crossing the GWIS 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.

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)
2 Apr 33.1 °C 41 % 34 km/h 0.1 mm High 22
3 Apr 33.1 °C 42 % 37 km/h 0.0 mm High 23
4 Apr 32.7 °C 44 % 37 km/h 0.1 mm High 23
5 Apr 32.3 °C 42 % 40 km/h 0.0 mm High 25
6 Apr 34.1 °C 37 % 41 km/h 0.0 mm High 25
7 Apr 34.0 °C 35 % 36 km/h 0.0 mm High 26
8 Apr 34.5 °C 33 % 38 km/h 0.0 mm High 29
9 Apr 34.2 °C 32 % 41 km/h 0.0 mm High 30
10 Apr 34.5 °C 28 % 41 km/h 0.0 mm High 33
11 Apr 34.4 °C 30 % 47 km/h 0.0 mm High 35
12 Apr 33.8 °C 35 % 38 km/h 0.0 mm High 32
13 Apr 33.7 °C 39 % 33 km/h 0.0 mm High 29
14 Apr 33.9 °C 36 % 31 km/h 0.0 mm High 29
15 Apr 33.9 °C 34 % 31 km/h 0.0 mm High 30
16 Apr 34.4 °C 33 % 28 km/h 0.0 mm High 29
17 Apr 33.4 °C 42 % 29 km/h 0.0 mm High 28
18 Apr after 31.7 °C 51 % 27 km/h 0.8 mm Moderate 16
19 Apr after 26.1 °C 74 % 34 km/h 4.6 mm Very low 2

Before and after, from space

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

Before · 26 Mar 2026
After · 24 Apr 2026

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 April 2026 the air beside the fire reached 218 µg/m³ of PM2.5. That day averaged 126: 8.4 times the WHO daily guideline (15).

PM2.5 peak218 µg/m³
Days over the guideline21 days
PM10224 µg/m³
Optical depth2.58
311234567891011121314151617181920
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 · 0Every 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 Laos ›

Frequently asked questions

How long did the Viengthong fire last?
GWIS (Copernicus) dates it between 2 April 2026 and 17 April 2026: 16 days between the first and last heat detection of the perimeter.
How much area did it burn?
The perimeter GWIS (Copernicus) rebuilt from heat detections is 11,863 hectares (118.6 km²). It is an estimate: official national figures may differ.
Which municipalities burned?
The fire entered 2 municipalities: Viengthong (9,088 ha, 2.3 %); Bolikhanh (2,834 ha, 1.1 %).
What was the weather like?
During the fire the temperature reached 34.5 °C, humidity dropped to 28 % and gusts hit 47 km/h. The fire danger index (FWI) reached 35, class High.
Where does this data come from?
From the GWIS (Copernicus) burnt perimeter, NASA FIRMS VIIRS hotspots and the administrative boundaries of Laos (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.

Satellite cross-check

History of this page · 2 Changes in area, dates, name, official record or merged pages, compared every night since 24 October 2026.
  1. Start date: 26 March 2026 → 2 April 2026.
  2. Name: Bolikhanh → Viengthong.

RSS Changes to this page

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.

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How we know this
  • Perimeter: GWIS (Copernicus), rebuilt from heat detections rather than mapped on imagery.
  • Dates from the perimeter: the VIIRS detections inside it did not change them. No Suomi-NPP VIIRS detections on those dates.
  • We have not matched this page with any official record.
  • 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 comes from the Copernicus Global Wildfire Information System (GWIS), which rebuilds it from MODIS and VIIRS heat detections and publishes it under CC BY 4.0. It is not measured on imagery as in Europe, so it is an estimate. 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 ADM2 (Creative Commons Attribution 3.0 Intergovernmental Organisations (CC BY 3.0 IGO)). The area per municipality is computed by WorldFires by crossing the perimeter with those boundaries, so it may differ from each country’s official figure.