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LA · Laos · –

Ngeun fire, 17 March 2023 Ngeun, Hongsa

Out · last detection 13 Apr 2023, 05:55 UTC

The fire started on 17 March 2023 in Ngeun, Laos, and satellites saw it burning for 27 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 10,401 hectares from heat detections, spread across 2 municipalities.

It is the 9th largest in Xaignabouli since 2016 (of 127 with a page). Number 23 in Laos in 2023, of 239.

Compare with…
Burnt area
10,401ha
GWIS perimeter (Copernicus)
Duration
27days
17 Mar 2023 – 12 Apr 2023
Municipalities hit
2
districts
Started on
17 Mar
2023
Heat detections
616
in a single hotspot: 243 MW
Danger at start
7
Low · FWI index
Average daily power
282MW
detected power per day, on average

Where it burned

HOTSPOTS BY DAY 17 Mar12 Apr
13 Apr 2023

How it evolved, day by day

17 Mar 2023 · 9 MW · 2 18 Mar 2023 · 33 MW · 4 20 Mar 2023 · 93 MW · 4 21 Mar 2023 · 243 MW · 9 22 Mar 2023 · 149 MW · 31 23 Mar 2023 · 45 MW · 16 24 Mar 2023 · 455 MW · 30 25 Mar 2023 · 102 MW · 16 26 Mar 2023 · 1,505 MW · 41 27 Mar 2023 · 591 MW · 61 28 Mar 2023 · 582 MW · 65 29 Mar 2023 · 308 MW · 42 30 Mar 2023 · 555 MW · 23 31 Mar 2023 · 1,215 MW · 96 1 Apr 2023 · 124 MW · 26 2 Apr 2023 · 163 MW · 13 3 Apr 2023 · 198 MW · 15 4 Apr 2023 · 70 MW · 16 5 Apr 2023 · 640 MW · 47 6 Apr 2023 · 15 MW · 10 7 Apr 2023 · 60 MW · 13 8 Apr 2023 · 8 MW · 4 10 Apr 2023 · 5 MW · 3 11 Apr 2023 · 97 MW · 12 12 Apr 2023 · 63 MW · 16 13 Apr 2023 · 2 MW · 1
17 Mar 26 Mar 5 Apr 12 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

36°high
50km/h · peak gust
26%lowest humidity

It had gone 0 days without rain (1 mm or more) when it started. Rain came after the fire: 3.2 mm on 22 Apr.

This area had burned before

87% of the perimeter overlaps earlier fires recorded since 2016: 1,904 ha in 2016, 693 ha in 2017, 500 ha in 2018, 6,135 ha in 2019, 6,699 ha in 2020, 2,275 ha in 2021, 2,189 ha in 2022. Part of it burned more than once, so the yearly figures add up to more than the 9,022 ha that had burned before.

How big is it?

10 km
It burned the equivalent of 6.6% of the area of London (104 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. Ngeun where it started
    10,376 ha reached on 17 Mar
    14 %
  2. 213 ha reached on 24 Mar
    0.1 %

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.

People and buildings inside the perimeter

GHSL 2025
Built-up area1.1 ha
Residents≈ 350

Inside the perimeter there were about 1.1 hectares of built-up land and about 350 residents (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.

Source: Global Human Settlement Layer (GHS-BUILT-S and GHS-POP R2023A), European Commission Joint Research Centre (JRC), © European Union, CC BY 4.0. Sum inside the perimeter computed by WorldFires. human-settlement.emergency.copernicus.eu

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)
17 Mar 30.3 °C 44 % 28 km/h 0.5 mm Low 7
18 Mar 31.7 °C 41 % 34 km/h 0.2 mm Moderate 12
19 Mar 31.5 °C 44 % 34 km/h 0.3 mm Moderate 13
20 Mar 31.3 °C 38 % 42 km/h 0.0 mm Moderate 17
21 Mar 32.0 °C 37 % 46 km/h 0.0 mm Moderate 18
22 Mar 33.1 °C 29 % 50 km/h 0.0 mm High 24
23 Mar 33.3 °C 27 % 50 km/h 0.0 mm High 26
24 Mar 32.9 °C 30 % 40 km/h 0.0 mm High 24
25 Mar 32.7 °C 31 % 39 km/h 0.0 mm High 25
26 Mar 32.5 °C 30 % 42 km/h 0.0 mm High 26
27 Mar 32.4 °C 33 % 35 km/h 0.0 mm High 25
28 Mar 32.2 °C 35 % 41 km/h 0.1 mm High 27
29 Mar 32.5 °C 31 % 42 km/h 0.0 mm High 28
30 Mar 31.8 °C 36 % 37 km/h 0.0 mm High 26
31 Mar 32.2 °C 36 % 35 km/h 0.0 mm High 27
1 Apr 33.2 °C 33 % 40 km/h 0.0 mm High 28
2 Apr 34.1 °C 27 % 50 km/h 0.0 mm High 32
3 Apr 32.7 °C 30 % 47 km/h 0.0 mm High 32
4 Apr 33.4 °C 28 % 46 km/h 0.0 mm High 32
5 Apr 33.5 °C 26 % 36 km/h 0.0 mm High 30
6 Apr 34.3 °C 28 % 24 km/h 0.0 mm High 28
7 Apr 33.6 °C 31 % 33 km/h 0.0 mm High 30
8 Apr 32.5 °C 38 % 31 km/h 0.0 mm High 28
9 Apr 33.4 °C 44 % 34 km/h 0.3 mm High 27
10 Apr 35.2 °C 32 % 36 km/h 0.0 mm High 29
11 Apr 35.7 °C 29 % 35 km/h 0.0 mm High 31
12 Apr 35.7 °C 29 % 32 km/h 0.0 mm High 30
13 Apr after 35.6 °C 33 % 36 km/h 0.0 mm High 32
14 Apr after 36.4 °C 31 % 34 km/h 0.0 mm High 32
15 Apr after 36.3 °C 28 % 27 km/h 0.0 mm High 31
16 Apr after 35.3 °C 38 % 40 km/h 0.0 mm High 32
17 Apr after 34.4 °C 37 % 39 km/h 0.0 mm High 33
18 Apr after 36.7 °C 30 % 41 km/h 0.0 mm High 34
19 Apr after 37.0 °C 25 % 40 km/h 0.0 mm High 38
20 Apr after 35.6 °C 32 % 40 km/h 0.0 mm High 37
21 Apr after 35.4 °C 34 % 38 km/h 0.0 mm High 36
22 Apr after 34.4 °C 37 % 34 km/h 3.2 mm Moderate 12

Its twins: fires that started in the same weather

It started with an FWI of 6.8, a minimum humidity of 44% and rain the day before. Fires in the area that started in weather like this since 2016: 26.

FWI at the start 6.8
Minimum humidity 44 %
Days without rain 0
this fire chosen twins rest of the area
Almost identicalSimilar

Outlines of the closest twins

Hongsa fire, April 2018
2,052 ha 4 days FWI 7.4 Min. humidity 44 % 24 km away, in 2018

First rain (1 mm or more) after it ended: 18.1 mm on 15 Apr.

What happened to them

7 days
median duration
3,010 ha
median area
100 %
went past 1,000 ha
6.2 mm
rain at the end (median; 25 of 26 had it)

It was 3.5 times larger than the median of its twins and lasted 27 days, against 7 days.

None of its 26 twins burned more. The weather on the first day does not explain everything: the wind in the following days, the fuel and the firefighting also count. In 1 of 26, 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 6.2 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

3.2 mmfirst rain
22 Apr10 days after it ended
50km/h · max. gust

It was considered over on 12 Apr, and on 22 Apr 3.2 mm fell. We do not know whether the rain or the firefighters put it out. Twins with rain when they ended: 25 of 26, with a median of 6.2 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.

How we calculate it

Before and after, from space

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

Before · 10 Mar 2023
After · 19 Apr 2023

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 7 April 2023 the air beside the fire reached 187 µg/m³ of PM2.5. That day averaged 110: 7.3 times the WHO daily guideline (15).

PM2.5 peak187 µg/m³
Days over the guideline20 days
PM10267 µg/m³
Optical depth2.34
19 Mar24 Mar29 Mar3 Apr8 Apr
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 · 616Every 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 Ngeun fire last?
According to the heat detections seen by satellite inside the perimeter, it burned from 17 March 2023 to 12 April 2023 (27 days). The perimeter dates it from 21 March 2023 to 5 April 2023.
How much area did it burn?
The perimeter GWIS (Copernicus) rebuilt from heat detections is 10,401 hectares (104.0 km²). It is an estimate: official national figures may differ.
Which municipalities burned?
The fire entered 2 municipalities: Ngeun (10,376 ha, 14 %); Hongsa (213 ha, 0.1 %).
What was the weather like?
During the fire the temperature reached 35.7 °C, humidity dropped to 26 % and gusts hit 50 km/h. The fire danger index (FWI) reached 32, 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.
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: 26. Their median duration was 7 days and their median area 3,010 ha; 100 % went past 1,000 ha. None of its 26 twins burned more. The weather on the first day does not explain everything: the wind in the following days, the fuel and the firefighting also count. In 1 of 26, 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 6.2 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.

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. Last day with fire: 5 April 2023 → 12 April 2023.
  2. Start date: 21 March 2023 → 17 March 2023.

RSS Changes to this page With cross-checks and a citable version

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; 3 polygons grouped in this page.
  • Dates adjusted with the VIIRS detections inside the perimeter, which said 21 March 2023 to 5 April 2023. 616 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.
  • 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.

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.