How long did the Huoixai fire last?

According to the heat detections seen by satellite inside the perimeter, it burned from 24 March 2023 to 23 April 2023 (31 days). The perimeter dates it from 31 March 2023 to 16 April 2023.

How much area did it burn?

The perimeter GWIS (Copernicus) rebuilt from heat detections is 9,095 hectares (91.0 km²). It is an estimate: official national figures may differ.

Which municipalities burned?

The fire entered 2 municipalities: Pha Oudom (4,844 ha, 2.8 %); Huoixai (4,303 ha, 2.5 %).

What was the weather like?

During the fire the temperature reached 36.8 °C, humidity dropped to 21 % and gusts hit 44 km/h. The fire danger index (FWI) reached 38, 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.

LA · Laos · 2023-03-24 → 2023-04-23

Huoixai fire, March 2023 Pha Oudom, Huoixai

Out · last detection 24 Apr 2023, 18:18 UTC

The fire started on 24 March 2023 in Huoixai, Laos, and satellites saw it burning for 31 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 9,095 hectares from heat detections, spread across 2 municipalities.

It is the 7th largest in Bokeo since 2016 (of 73 with a page). Number 28 in Laos in 2023, of 239.

Compare with…

Suggestions: Pha Oudom · 2020 Pha Oudom · 2020 Pha Oudom · 2026 Pha Oudom · 2020

Burnt area: 9,095ha; GWIS perimeter (Copernicus)
Duration: 31days; 24 Mar 2023 – 23 Apr 2023
Municipalities hit: 2; districts
Started on: 24 Mar; 2023
Heat detections: 531; in a single hotspot: 133 MW
Danger at start: 27; High · FWI index
Average daily power: 107MW; detected power per day, on average

HOTSPOTS BY DAY 24 Mar23 Apr

Play back 24 Apr 2023

How it evolved, day by day

24 Mar 29 Mar 3 Apr 8 Apr 13 Apr 18 Apr 24 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

37°high

44km/h · peak gust

21%lowest humidity

It had gone 7 days without rain (1 mm or more) when it started. Rain came after the fire: 1.9 mm on 26 Apr.

This area had burned before

66% of the perimeter overlaps earlier fires recorded since 2016: 2 ha in 2017, 992 ha in 2019, 5,807 ha in 2020. Part of it burned more than once, so the yearly figures add up to more than the 6,038 ha that had burned before.

How big is it?

It burned the equivalent of 5.7% of the area of London (91 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

Pha Oudom

4,844 ha

2.8 %
Huoixai where it started

4,303 ha

2.5 %

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 area< 0.1 ha

Residents≈ 850

Inside the perimeter there were about 0.01 hectares of built-up land and about 850 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)
24 Mar	32.4 °C	28 %	36 km/h	0.0 mm	High 27
25 Mar	32.1 °C	30 %	33 km/h	0.0 mm	High 27
26 Mar	32.3 °C	27 %	37 km/h	0.0 mm	High 28
27 Mar	32.0 °C	32 %	34 km/h	0.0 mm	High 28
28 Mar	33.6 °C	25 %	44 km/h	0.0 mm	High 33
29 Mar	32.5 °C	28 %	37 km/h	0.0 mm	High 31
30 Mar	32.0 °C	31 %	35 km/h	0.0 mm	High 30
31 Mar	32.7 °C	30 %	32 km/h	0.0 mm	High 31
1 Apr	33.4 °C	30 %	37 km/h	0.0 mm	High 32
2 Apr	33.4 °C	28 %	43 km/h	0.0 mm	High 35
3 Apr	32.5 °C	27 %	44 km/h	0.0 mm	High 35
4 Apr	32.7 °C	26 %	41 km/h	0.0 mm	High 35
5 Apr	33.4 °C	21 %	35 km/h	0.0 mm	High 35
6 Apr	33.8 °C	26 %	27 km/h	0.0 mm	High 33
7 Apr	33.3 °C	30 %	35 km/h	0.0 mm	High 35
8 Apr	33.5 °C	35 %	33 km/h	0.0 mm	High 32
9 Apr	34.7 °C	33 %	36 km/h	0.0 mm	High 34
10 Apr	35.7 °C	26 %	34 km/h	0.0 mm	High 34
11 Apr	35.9 °C	25 %	32 km/h	0.0 mm	High 34
12 Apr	35.6 °C	23 %	32 km/h	0.0 mm	High 36
13 Apr	35.6 °C	29 %	34 km/h	0.0 mm	High 38
14 Apr	36.8 °C	24 %	32 km/h	0.0 mm	High 37
15 Apr	36.1 °C	24 %	28 km/h	0.0 mm	High 36
16 Apr	35.7 °C	31 %	36 km/h	0.0 mm	High 38
17 Apr	35.0 °C	33 %	34 km/h	0.0 mm	High 36
18 Apr	36.8 °C	27 %	36 km/h	0.0 mm	High 37
19 Apr	36.8 °C	24 %	35 km/h	0.0 mm	Very high 38
20 Apr	35.8 °C	26 %	36 km/h	0.0 mm	Very high 38
21 Apr	35.9 °C	27 %	34 km/h	0.0 mm	Very high 38
22 Apr	34.8 °C	32 %	34 km/h	2.3 mm	Moderate 19
23 Apr	36.6 °C	23 %	31 km/h	0.1 mm	High 35
24 Apr after	33.4 °C	34 %	34 km/h	0.0 mm	High 32
25 Apr after	35.8 °C	25 %	26 km/h	0.0 mm	High 32
26 Apr after	31.8 °C	44 %	40 km/h	1.9 mm	Moderate 14

Before and after, from space

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

↔

Before · 17 Mar 2023

After · 30 Apr 2023

Before After

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 · 531Every 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 time	Satellite	FRP (MW)	Lat	Lon

Other fires nearby

All fires in Laos ›

Frequently asked questions

How long did the Huoixai fire last?: According to the heat detections seen by satellite inside the perimeter, it burned from 24 March 2023 to 23 April 2023 (31 days). The perimeter dates it from 31 March 2023 to 16 April 2023.
How much area did it burn?: The perimeter GWIS (Copernicus) rebuilt from heat detections is 9,095 hectares (91.0 km²). It is an estimate: official national figures may differ.
Which municipalities burned?: The fire entered 2 municipalities: Pha Oudom (4,844 ha, 2.8 %); Huoixai (4,303 ha, 2.5 %).
What was the weather like?: During the fire the temperature reached 36.8 °C, humidity dropped to 21 % and gusts hit 44 km/h. The fire danger index (FWI) reached 38, 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

NASA FIRMS ↗
GWIS · Copernicus ↗

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 31 March 2023 to 16 April 2023. 531 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.

Where it burned