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Sanxay fire, 3 March 2023 Sanxay, Phouvong

Out · last detection 15 Mar 2023, 06:37 UTC

The fire started on 3 March 2023 in Sanxay, Laos, and satellites saw it burning for 13 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 3,847 hectares from heat detections, spread across 2 municipalities.

It is the 9th largest in Attapeu since 2016 (of 37 with a page). Number 76 in Laos in 2023, of 239.

Compare with…

Suggestions: Phouvong · 2024Xaysetha · 2026Xaysetha · 2022Xaysetha · 2021

Burnt area
3,847ha
GWIS perimeter (Copernicus)
Duration
13days
3 Mar 2023 – 15 Mar 2023
Municipalities hit
2
districts
Started on
3 Mar
2023
Heat detections
77
in a single hotspot: 264 MW
Danger at start
27
High · FWI index
Average daily power
237MW
detected power per day, on average

Where it burned

HOTSPOTS BY DAY 3 Mar15 Mar
15 Mar 2023

How it evolved, day by day

3 Mar 2023 · 8 MW · 1 4 Mar 2023 · 157 MW · 7 6 Mar 2023 · 1,713 MW · 42 7 Mar 2023 · 91 MW · 7 9 Mar 2023 · 124 MW · 13 10 Mar 2023 · 14 MW · 2 11 Mar 2023 · 8 MW · 2 14 Mar 2023 · 1 MW · 1 15 Mar 2023 · 18 MW · 2
3 Mar 6 Mar 9 Mar 11 Mar 15 Mar

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

The weather it burned in

37°high
40km/h · peak gust
21%lowest humidity

It had gone 15 days without rain (1 mm or more) when it started.

This area had burned before

48% of the perimeter overlaps earlier fires recorded since 2016: 1,070 ha in 2018, 1,333 ha in 2019, 1,143 ha in 2020, 1,103 ha in 2021. Part of it burned more than once, so the yearly figures add up to more than the 1,836 ha that had burned before.

How big is it?

10 km
It burned the equivalent of 2.4% of the area of London (38 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. Sanxay where it started
    3,372 ha reached on 3 Mar
    1.2 %
  2. Phouvong
    495 ha reached on 6 Mar
    0.2 %

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 area0.48 ha
Residents≈ 40

Inside the perimeter there were about 0.48 hectares of built-up land and about 40 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)
3 Mar 33.5 °C 30 % 35 km/h 0.0 mm High 27
4 Mar 32.7 °C 31 % 35 km/h 0.0 mm High 26
5 Mar 32.0 °C 31 % 33 km/h 0.0 mm High 28
6 Mar 33.3 °C 28 % 29 km/h 0.0 mm High 27
7 Mar 34.2 °C 28 % 27 km/h 0.0 mm High 28
8 Mar 36.2 °C 21 % 30 km/h 0.0 mm High 34
9 Mar 33.9 °C 32 % 33 km/h 0.0 mm High 32
10 Mar 36.2 °C 24 % 24 km/h 0.0 mm High 32
11 Mar 36.9 °C 26 % 32 km/h 0.0 mm High 33
12 Mar 35.6 °C 26 % 40 km/h 0.0 mm High 36
13 Mar 33.5 °C 31 % 40 km/h 0.0 mm High 35
14 Mar 35.3 °C 27 % 24 km/h 0.0 mm High 31
15 Mar 37.1 °C 27 % 22 km/h 0.0 mm High 31
16 Mar after 37.2 °C 29 % 20 km/h 0.0 mm High 32
17 Mar after 38.1 °C 22 % 26 km/h 0.0 mm High 34
18 Mar after 36.8 °C 32 % 27 km/h 0.0 mm High 32
19 Mar after 37.5 °C 31 % 26 km/h 0.0 mm High 33
20 Mar after 36.7 °C 31 % 28 km/h 0.0 mm High 34
21 Mar after 36.8 °C 31 % 32 km/h 0.2 mm High 35
22 Mar after 38.3 °C 29 % 31 km/h 0.0 mm High 36
23 Mar after 36.5 °C 36 % 28 km/h 0.5 mm High 32
24 Mar after 36.3 °C 36 % 27 km/h 0.1 mm High 31
25 Mar after 36.1 °C 40 % 30 km/h 0.2 mm High 30

Before and after, from space

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

Before · 24 Feb 2023
After · 22 Mar 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 11 March 2023 the air beside the fire reached 72 µg/m³ of PM2.5. That day averaged 30: 2.0 times the WHO daily guideline (15).

PM2.5 peak72 µg/m³
Days over the guideline11 days
PM10104 µg/m³
Optical depth0.73
123456789101112131415161718
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 · 77Every 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 Sanxay fire last?
According to the heat detections seen by satellite inside the perimeter, it burned from 3 March 2023 to 15 March 2023 (13 days). The perimeter dates it from 3 March 2023 to 10 March 2023.
How much area did it burn?
The perimeter GWIS (Copernicus) rebuilt from heat detections is 3,847 hectares (38.5 km²). It is an estimate: official national figures may differ.
Which municipalities burned?
The fire entered 2 municipalities: Sanxay (3,372 ha, 1.2 %); Phouvong (495 ha, 0.2 %).
What was the weather like?
During the fire the temperature reached 37.1 °C, humidity dropped to 21 % and gusts hit 40 km/h. The fire danger index (FWI) reached 36, 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.

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 adjusted with the VIIRS detections inside the perimeter, which said 3 March 2023 to 10 March 2023. 77 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.