How long did the Longsane fire last?

According to the heat detections seen by satellite inside the perimeter, it burned from 27 March 2026 to 17 April 2026 (22 days). The perimeter dates it from 31 March 2026 to 17 April 2026.

How much area did it burn?

The perimeter GWIS (Copernicus) rebuilt from heat detections is 5,970 hectares (59.7 km²). It is an estimate: official national figures may differ.

Which municipalities burned?

The fire only entered Longsane (6,001 ha, 4.3 %).

What was the weather like?

During the fire the temperature reached 37.1 °C, humidity dropped to 23 % and gusts hit 43 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.

LA · Laos · 2026-03-27 → 2026-04-17

Longsane fire, 27 March 2026 Longsane

Out · last detection 17 Apr 2026, 07:15 UTC

The fire started on 27 March 2026 in Longsane, Laos, and satellites saw it burning for 22 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 5,970 hectares from heat detections, spread across a single municipality.

It is the 5th largest in Xaisomboun since 2016 (of 28 with a page). Number 68 in Laos in 2026, of 287.

Burnt area: 5,970ha; GWIS perimeter (Copernicus)
Duration: 22days; 27 Mar 2026 – 17 Apr 2026
Municipalities hit: 1; districts
Started on: 27 Mar; 2026
Heat detections: 303; in a single hotspot: 84 MW
Danger at start: 14; Moderate · FWI index
Energy released: 2.4GW; sum of detected power

Play back 17 Apr 2026

HOTSPOTS BY DAY 27 Mar17 Apr

How it evolved, day by day

272829311234567891011121314151617

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

43km/h · peak gust

23%lowest humidity

It had gone 3 days without rain (1 mm or more) when it started. Rain came after the fire: 12.7 mm on 19 Apr.

This area had burned before

29% of the perimeter overlaps earlier fires recorded since 2016: 1,731 ha in 2023.

What happened to each town

Longsane where it started

6,001 ha reached on 27 Mar

4.3 %

Burnt area inside each municipality, from crossing the GWIS perimeter with administrative boundaries. The distance is from the town centre to the nearest fire: staying a kilometre away does not mean it reached the houses.

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)
27 Mar	34.2 °C	39 %	31 km/h	0.0 mm	Moderate 14
28 Mar	34.4 °C	45 %	29 km/h	0.6 mm	Moderate 12
29 Mar	33.2 °C	45 %	35 km/h	1.9 mm	Low 7
30 Mar	32.2 °C	47 %	35 km/h	0.0 mm	Moderate 11
31 Mar	33.6 °C	38 %	35 km/h	0.0 mm	Moderate 16
1 Apr	33.5 °C	40 %	23 km/h	0.0 mm	Moderate 15
2 Apr	34.0 °C	42 %	31 km/h	0.0 mm	Moderate 17
3 Apr	34.0 °C	42 %	36 km/h	0.0 mm	Moderate 18
4 Apr	33.4 °C	44 %	35 km/h	0.0 mm	Moderate 18
5 Apr	34.1 °C	41 %	36 km/h	0.0 mm	Moderate 19
6 Apr	35.3 °C	36 %	34 km/h	0.0 mm	Moderate 20
7 Apr	35.6 °C	33 %	34 km/h	0.0 mm	High 22
8 Apr	36.2 °C	28 %	40 km/h	0.0 mm	High 27
9 Apr	36.5 °C	26 %	40 km/h	0.0 mm	High 29
10 Apr	36.3 °C	24 %	41 km/h	0.0 mm	High 31
11 Apr	36.0 °C	28 %	43 km/h	0.0 mm	High 33
12 Apr	35.8 °C	29 %	35 km/h	0.0 mm	High 31
13 Apr	36.2 °C	33 %	35 km/h	0.0 mm	High 30
14 Apr	36.4 °C	30 %	33 km/h	0.0 mm	High 31
15 Apr	36.7 °C	28 %	36 km/h	0.0 mm	High 33
16 Apr	37.1 °C	23 %	32 km/h	0.0 mm	High 33
17 Apr	35.4 °C	31 %	27 km/h	0.0 mm	High 32
18 Apr after	32.4 °C	53 %	29 km/h	0.5 mm	High 23
19 Apr after	29.3 °C	67 %	34 km/h	12.7 mm	Very low 1

Before and after, from space

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

↔

Before · 20 Mar 2026

After · 24 Apr 2026

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.

The smoke

CAMS · Copernicus

On 13 April 2026 the air beside the fire reached 335 µg/m³ of PM2.5. That day averaged 194: 13 times the WHO daily guideline (15).

PM2.5 peak335 µg/m³

Days over the guideline27 days

PM10353 µg/m³

Optical depth2.89

WHO 15

252627282930311234567891011121314151617181920

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 · 303Every 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 Longsane fire last?: According to the heat detections seen by satellite inside the perimeter, it burned from 27 March 2026 to 17 April 2026 (22 days). The perimeter dates it from 31 March 2026 to 17 April 2026.
How much area did it burn?: The perimeter GWIS (Copernicus) rebuilt from heat detections is 5,970 hectares (59.7 km²). It is an estimate: official national figures may differ.
Which municipalities burned?: The fire only entered Longsane (6,001 ha, 4.3 %).
What was the weather like?: During the fire the temperature reached 37.1 °C, humidity dropped to 23 % and gusts hit 43 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

NASA FIRMS ↗
GWIS · Copernicus ↗

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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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