Pak Xeng fire, 3 April 2023 Pak Xeng, Viengkham
The fire started on 3 April 2023 in Pak Xeng, Laos, and satellites saw it burning for 27 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 19,543 hectares from heat detections, spread across 2 municipalities.
It is the 6th largest in Luang Prabang since 2016 (of 295 with a page). Number 9 in Laos in 2023, of 239.
Compare with…
- Burnt area
- 19,543ha
- GWIS perimeter (Copernicus)
- Duration
- 27days
- 3 Apr 2023 – 29 Apr 2023
- Municipalities hit
- 2
- districts
- Started on
- 3 Apr
- 2023
- Heat detections
- 979
- in a single hotspot: 879 MW
- Danger at start
- 18
- Moderate · FWI index
- Average daily power
- 1.2GW
- detected power per day, on average
Where it burned
How it evolved, day by day
Fire radiative power detected each day, in megawatts, and number of hotspots. The magenta bar marks the peak day.
The weather it burned in
It had gone one day without rain (1 mm or more) when it started. Rain came after the fire: 12.0 mm on 26 Apr.
This area had burned before
63% of the perimeter overlaps earlier fires recorded since 2016: 2,734 ha in 2016, 1,577 ha in 2017, 3,083 ha in 2018, 5,003 ha in 2019, 1,564 ha in 2020, 4,197 ha in 2021, 6,106 ha in 2022. Part of it burned more than once, so the yearly figures add up to more than the 12,216 ha that had burned before.
- 4,156 ha Pak Xeng fire, April 2022 6,783 ha in total; the hectares shown are those it shares with this fire
- 2,467 ha Viengkham fire, April 2019 8,338 ha in total; the hectares shown are those it shares with this fire
- 1,973 ha Pak Xeng fire, April 2016 2,401 ha in total; the hectares shown are those it shares with this fire
- 1,507 ha Pak Xeng fire, April 2018 3,823 ha in total; the hectares shown are those it shares with this fire
- 1,164 ha Pak Xeng fire, April 2018 2,032 ha in total; the hectares shown are those it shares with this fire
- 1,028 ha Pak Xeng fire, April 2019 7,284 ha in total; the hectares shown are those it shares with this fire
- 867 ha Pak Xeng fire, April 2017 3,931 ha in total; the hectares shown are those it shares with this fire
- 490 ha Pak Xeng fire, April 2020 2,477 ha in total; the hectares shown are those it shares with this fire
How big is it?
London boundary: geoBoundaries · Office for National Statistics (Open Government Licence v3.0).
Paris boundary: geoBoundaries · Institut national de l'information géographique et forestière (IGN-F) (Etalab Open License 2.0).
Madrid boundary: geoBoundaries · Open Data ESRI, IGN Central Registry of Cartography Area (CC BY 4.0).
Berlin boundary: geoBoundaries · Federal Agency for Cartography and Geodesy (dl-de/by-2-0).
This compares size, not location: both shapes are at the same scale, north up, centred on each other.
What happened to each town
-
Pak Xeng where it started19,642 ha reached on 3 Apr12 %
-
1 ha reached on 6 Apr0.0 %
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 2025Inside the perimeter there were about 8.6 hectares of built-up land and about 4,200 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) |
|---|---|---|---|---|---|
| 10 Apr | 34.8 °C | 40 % | 34 km/h | 0.0 mm | Moderate 18 |
| 11 Apr | 36.3 °C | 36 % | 31 km/h | 0.0 mm | Moderate 21 |
| 12 Apr | 36.0 °C | 36 % | 30 km/h | 0.0 mm | High 21 |
| 13 Apr | 35.8 °C | 40 % | 31 km/h | 0.0 mm | High 23 |
| 14 Apr | 36.6 °C | 39 % | 30 km/h | 0.0 mm | High 23 |
| 15 Apr | 36.8 °C | 34 % | 29 km/h | 0.0 mm | High 26 |
| 16 Apr | 34.6 °C | 46 % | 34 km/h | 0.5 mm | High 23 |
| 17 Apr | 35.2 °C | 43 % | 41 km/h | 0.0 mm | High 26 |
| 18 Apr | 38.0 °C | 31 % | 39 km/h | 0.0 mm | High 30 |
| 19 Apr | 38.3 °C | 27 % | 39 km/h | 0.0 mm | High 33 |
| 20 Apr | 37.7 °C | 32 % | 36 km/h | 0.0 mm | High 33 |
| 21 Apr | 37.1 °C | 35 % | 35 km/h | 0.1 mm | High 33 |
| 22 Apr | 36.0 °C | 39 % | 36 km/h | 0.3 mm | High 30 |
| 23 Apr | 38.1 °C | 25 % | 31 km/h | 0.0 mm | High 33 |
| 24 Apr | 35.3 °C | 37 % | 35 km/h | 0.0 mm | High 30 |
| 25 Apr | 36.4 °C | 39 % | 34 km/h | 0.6 mm | High 27 |
| 26 Apr | 28.7 °C | 64 % | 32 km/h | 12.0 mm | Very low 1 |
Before and after, from space
Drag the line to compare the same ground before the fire and after it.
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 · CopernicusOn 6 April 2023 the air beside the fire reached 542 µg/m³ of PM2.5. That day averaged 291: 19 times the WHO daily guideline (15).
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 · 979Every satellite heat detection, one by one, with time, satellite, power and coordinates.
| Date and time | Satellite | FRP (MW) | Lat | Lon |
|---|
Other fires nearby
Frequently asked questions
- How long did the Pak Xeng fire last?
- According to the heat detections seen by satellite inside the perimeter, it burned from 3 April 2023 to 29 April 2023 (27 days). The perimeter dates it from 10 April 2023 to 25 April 2023.
- How much area did it burn?
- The perimeter GWIS (Copernicus) rebuilt from heat detections is 19,543 hectares (195.4 km²). It is an estimate: official national figures may differ.
- Which municipalities burned?
- The fire entered 2 municipalities: Pak Xeng (19,642 ha, 12 %); Viengkham (1 ha, 0.0 %).
- What was the weather like?
- During the fire the temperature reached 38.3 °C, humidity dropped to 25 % and gusts hit 41 km/h. The fire danger index (FWI) reached 33, 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 Changes in area, dates, name, official record or merged pages, compared every night since 24 October 2026.
No changes since 24 October 2026.
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
How we know this
- Perimeter: GWIS (Copernicus), rebuilt from heat detections rather than mapped on imagery; 4 polygons grouped in this page.
- Dates adjusted with the VIIRS detections inside the perimeter, which said 10 April 2023 to 25 April 2023. 979 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.
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.