Longsane fire, 20 March 2023 Thaphabath, Longsane
The fire started on 20 March 2023 in Longsane, Laos, and satellites saw it burning for 8 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 3,328 hectares from heat detections, spread across 2 municipalities.
It is the 11th largest in Xaisomboun since 2016 (of 28 with a page). Number 88 in Laos in 2023, of 239.
Compare with…
- Burnt area
- 3,328ha
- GWIS perimeter (Copernicus)
- Duration
- 8days
- 20 Mar 2023 – 27 Mar 2023
- Municipalities hit
- 2
- districts
- Started on
- 20 Mar
- 2023
- Heat detections
- 135
- in a single hotspot: 158 MW
- Danger at start
- 24
- High · FWI index
- Average daily power
- 204MW
- 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 28 days without rain (1 mm or more) when it started. Rain came after the fire: 2.6 mm on 29 Mar.
This area had burned before
No earlier perimeters overlap this fire since 2016, when the satellite record begins.
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
-
1,829 ha1.2 %
-
Longsane where it started1,518 ha1.1 %
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 2025Inside the perimeter there were about 1.2 hectares of built-up land and about 2,200 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) |
|---|---|---|---|---|---|
| 20 Mar | 34.5 °C | 34 % | 37 km/h | 0.0 mm | High 24 |
| 21 Mar | 34.3 °C | 36 % | 42 km/h | 0.7 mm | High 24 |
| 22 Mar | 35.8 °C | 27 % | 45 km/h | 0.0 mm | High 31 |
| 23 Mar | 35.3 °C | 26 % | 45 km/h | 0.0 mm | High 32 |
| 24 Mar | 35.6 °C | 28 % | 38 km/h | 0.0 mm | High 31 |
| 25 Mar | 35.9 °C | 26 % | 38 km/h | 0.0 mm | High 31 |
| 26 Mar | 34.4 °C | 28 % | 38 km/h | 0.0 mm | High 32 |
| 27 Mar | 32.2 °C | 45 % | 29 km/h | 0.2 mm | High 25 |
| 28 Mar after | 30.3 °C | 51 % | 37 km/h | 0.3 mm | High 21 |
| 29 Mar after | 28.3 °C | 64 % | 34 km/h | 2.6 mm | Very low 4 |
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.
Detections table · 135Every satellite heat detection, one by one, with time, satellite, power and coordinates.
| Date and time | Satellite | FRP (MW) | Lat | Lon |
|---|
Other fires nearby
- 5,970 haLongsane27 March 2026 · 22 days · 9 km away
- 16,171 haThaphabath14 March 2023 · 15 days · 13 km away
- 14,089 haLongsane26 March 2026 · 28 days · 20 km away
- 75,002 haXaythanyMarch 2026 · 27 days · 26 km away
- 6,483 haThoulakhomApril 2026 · 19 days · 33 km away
- 6,473 haAnouvongMarch 2026 · 24 days · 37 km away
Frequently asked questions
- How long did the Longsane fire last?
- GWIS (Copernicus) dates it between 20 March 2023 and 27 March 2023: 8 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 3,328 hectares (33.3 km²). It is an estimate: official national figures may differ.
- Which municipalities burned?
- The fire entered 2 municipalities: Thaphabath (1,829 ha, 1.2 %); Longsane (1,518 ha, 1.1 %).
- What was the weather like?
- During the fire the temperature reached 35.9 °C, humidity dropped to 26 % and gusts hit 45 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.
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.
- Dates from the perimeter: the VIIRS detections inside it did not change them. 135 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.