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Xay fire, March 2023 Xay

Out · last detection 23 Apr 2023, 18:37 UTC

The fire started on 26 March 2023 in Xay, Laos, and satellites saw it burning for 28 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 6,125 hectares from heat detections, spread across a single municipality.

It is the 40th largest in Oudomxay since 2016 (of 239 with a page). Number 46 in Laos in 2023, of 239.

Compare with…

Suggestions: Xay · 2021Xay · 2022Namor · 2022Namor · 2019

Burnt area
6,125ha
GWIS perimeter (Copernicus)
Duration
28days
26 Mar 2023 – 22 Apr 2023
Municipalities hit
1
districts
Started on
26 Mar
2023
Heat detections
375
in a single hotspot: 260 MW
Danger at start
31
High · FWI index
Average daily power
461MW
detected power per day, on average

Where it burned

HOTSPOTS BY DAY 26 Mar22 Apr
23 Apr 2023

How it evolved, day by day

26 Mar 2023 · 116 MW · 4 27 Mar 2023 · 351 MW · 4 29 Mar 2023 · 10 MW · 2 31 Mar 2023 · 13 MW · 1 2 Apr 2023 · 87 MW · 7 3 Apr 2023 · 292 MW · 18 4 Apr 2023 · 52 MW · 6 5 Apr 2023 · 2,240 MW · 56 6 Apr 2023 · 1,216 MW · 22 8 Apr 2023 · 2,337 MW · 52 9 Apr 2023 · 1,522 MW · 45 10 Apr 2023 · 682 MW · 35 11 Apr 2023 · 595 MW · 24 12 Apr 2023 · 134 MW · 7 13 Apr 2023 · 50 MW · 6 14 Apr 2023 · 89 MW · 10 15 Apr 2023 · 42 MW · 5 16 Apr 2023 · 48 MW · 8 17 Apr 2023 · 847 MW · 12 18 Apr 2023 · 523 MW · 17 19 Apr 2023 · 8 MW · 1 20 Apr 2023 · 49 MW · 10 21 Apr 2023 · 78 MW · 8 22 Apr 2023 · 41 MW · 9 23 Apr 2023 · 108 MW · 6
26 Mar 2 Apr 6 Apr 8 Apr 11 Apr 15 Apr 19 Apr 23 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

38°high
45km/h · peak gust
21%lowest humidity

It had gone 9 days without rain (1 mm or more) when it started. Rain came after the fire: 6.2 mm on 26 Apr.

This area had burned before

78% of the perimeter overlaps earlier fires recorded since 2016: 1,315 ha in 2016, 47 ha in 2017, 1,747 ha in 2019, 68 ha in 2020, 3,463 ha in 2021, 291 ha in 2022. Part of it burned more than once, so the yearly figures add up to more than the 4,775 ha that had burned before.

How big is it?

10 km
It burned the equivalent of 3.9% of the area of London (61 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. Xay where it started
    6,150 ha
    2.9 %

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 area0.55 ha
Residents≈ 1,100

Inside the perimeter there were about 0.55 hectares of built-up land and about 1,100 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)
26 Mar 33.3 °C 26 % 40 km/h 0.0 mm High 31
27 Mar 32.9 °C 32 % 35 km/h 0.2 mm High 31
28 Mar 33.1 °C 31 % 41 km/h 0.0 mm High 33
29 Mar 32.6 °C 33 % 40 km/h 0.2 mm High 32
30 Mar 32.5 °C 32 % 37 km/h 0.0 mm High 32
31 Mar 33.2 °C 31 % 34 km/h 0.0 mm High 31
1 Apr 34.3 °C 30 % 37 km/h 0.0 mm High 33
2 Apr 33.9 °C 30 % 45 km/h 0.0 mm High 36
3 Apr 33.4 °C 28 % 43 km/h 0.0 mm High 36
4 Apr 33.8 °C 26 % 43 km/h 0.0 mm High 37
5 Apr 34.4 °C 21 % 33 km/h 0.0 mm High 36
6 Apr 34.5 °C 28 % 25 km/h 0.0 mm High 33
7 Apr 34.0 °C 32 % 37 km/h 0.0 mm High 35
8 Apr 33.0 °C 39 % 32 km/h 0.0 mm High 30
9 Apr 34.0 °C 40 % 40 km/h 0.2 mm High 31
10 Apr 36.1 °C 27 % 34 km/h 0.0 mm High 35
11 Apr 36.6 °C 27 % 29 km/h 0.0 mm High 34
12 Apr 36.3 °C 26 % 31 km/h 0.0 mm High 36
13 Apr 36.1 °C 31 % 33 km/h 0.0 mm High 37
14 Apr 36.9 °C 28 % 30 km/h 0.0 mm High 36
15 Apr 36.4 °C 28 % 25 km/h 0.0 mm High 34
16 Apr 35.5 °C 38 % 41 km/h 0.0 mm High 34
17 Apr 35.4 °C 34 % 37 km/h 0.0 mm High 36
18 Apr 37.6 °C 27 % 38 km/h 0.0 mm Very high 38
19 Apr 37.6 °C 24 % 36 km/h 0.0 mm Very high 40
20 Apr 36.8 °C 25 % 37 km/h 0.0 mm Very high 41
21 Apr 37.0 °C 26 % 35 km/h 0.0 mm Very high 40
22 Apr 35.3 °C 35 % 37 km/h 2.3 mm Moderate 20
23 Apr after 36.9 °C 27 % 34 km/h 0.0 mm High 32
24 Apr after 33.8 °C 35 % 36 km/h 0.0 mm High 31
25 Apr after 35.7 °C 33 % 28 km/h 0.1 mm High 30
26 Apr after 31.5 °C 50 % 36 km/h 6.2 mm Low 5

Before and after, from space

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

Before · 19 Mar 2023
After · 29 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.

Detections table · 375Every 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 Xay fire last?
According to the heat detections seen by satellite inside the perimeter, it burned from 26 March 2023 to 22 April 2023 (28 days). The perimeter dates it from 2 April 2023 to 15 April 2023.
How much area did it burn?
The perimeter GWIS (Copernicus) rebuilt from heat detections is 6,125 hectares (61.2 km²). It is an estimate: official national figures may differ.
Which municipalities burned?
The fire only entered Xay (6,150 ha, 2.9 %).
What was the weather like?
During the fire the temperature reached 37.6 °C, humidity dropped to 21 % and gusts hit 45 km/h. The fire danger index (FWI) reached 41, class Very 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 2 April 2023 to 15 April 2023. 375 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.