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Siem Bouk fire, March 2026 Siem Bouk

Out · last detection 27 Apr 2026, 18:20 UTC

The fire started on 14 March 2026 in Siem Bouk, Cambodia, and satellites saw it burning for 45 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 2,997 hectares from heat detections, spread across a single municipality.

This page is probably a fire complex, not a single fire. GWIS merges into one perimeter the fires that touch over weeks, which in large burning seasons can join dozens of separate fires. The total area is reliable; the origin and dates refer to the whole complex.

It is the 68th largest in Stung Treng since 2016 (of 130 with a page). Number 55 in Cambodia in 2026, of 115.

Burnt area
2,997ha
GWIS perimeter (Copernicus)
Duration
45days
14 Mar 2026 – 27 Apr 2026
Municipalities hit
1
districts
Started on
14 Mar
2026
Heat detections
515
in a single hotspot: 228 MW
Danger at start
20
Moderate · FWI index
Energy released
6.0GW
sum of detected power

Where it burned

27 Apr 2026
HOTSPOTS BY DAY 14 Mar27 Apr

How it evolved, day by day

14151617192021222324252627282930311234567910111213141517212223242527

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
34%lowest humidity

It had gone 8 days without rain (1 mm or more) when it started. Rain came after the fire: 3.0 mm on 28 Apr.

This area had burned before

51% of the perimeter overlaps earlier fires recorded since 2016: 1,238 ha in 2016, 471 ha in 2020, 158 ha in 2021, 260 ha in 2023. Part of it burned more than once, so the yearly figures add up to more than the 1,522 ha that had burned before.

What happened to each town

  1. Siem Bouk where it started
    3,013 ha reached on 14 Mar
    2.0 %

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)
14 Mar 33.9 °C 41 % 45 km/h 0.0 mm Moderate 20
15 Mar 34.6 °C 36 % 37 km/h 0.0 mm Moderate 20
16 Mar 34.8 °C 36 % 34 km/h 0.0 mm Moderate 20
17 Mar 34.8 °C 37 % 29 km/h 0.0 mm Moderate 20
18 Mar 34.2 °C 42 % 22 km/h 0.0 mm Moderate 19
19 Mar 34.8 °C 44 % 23 km/h 0.0 mm Moderate 19
20 Mar 32.8 °C 54 % 28 km/h 0.4 mm Moderate 17
21 Mar 35.5 °C 43 % 19 km/h 0.0 mm Moderate 16
22 Mar 36.1 °C 38 % 20 km/h 0.0 mm Moderate 20
23 Mar 33.8 °C 46 % 25 km/h 0.0 mm Moderate 19
24 Mar 35.7 °C 39 % 25 km/h 0.0 mm Moderate 21
25 Mar 35.6 °C 41 % 23 km/h 0.0 mm Moderate 21
26 Mar 36.0 °C 39 % 23 km/h 0.0 mm Moderate 21
27 Mar 35.7 °C 40 % 28 km/h 0.0 mm High 23
28 Mar 37.3 °C 38 % 22 km/h 0.0 mm High 24
29 Mar 35.5 °C 41 % 27 km/h 0.0 mm High 25
30 Mar 36.7 °C 35 % 27 km/h 0.0 mm High 26
31 Mar 36.5 °C 38 % 29 km/h 0.0 mm High 28
1 Apr 36.6 °C 39 % 27 km/h 0.0 mm High 27
2 Apr 35.6 °C 44 % 30 km/h 0.0 mm High 27
3 Apr 35.8 °C 41 % 30 km/h 0.0 mm High 28
4 Apr 36.2 °C 39 % 32 km/h 0.0 mm High 30
5 Apr 37.2 °C 34 % 31 km/h 0.0 mm High 29
6 Apr 37.1 °C 38 % 36 km/h 0.0 mm High 32
7 Apr 38.0 °C 34 % 31 km/h 0.0 mm High 32
8 Apr 38.0 °C 36 % 31 km/h 0.0 mm High 30
9 Apr 36.1 °C 45 % 34 km/h 0.0 mm High 31
10 Apr 37.0 °C 42 % 31 km/h 0.0 mm High 31
11 Apr 36.8 °C 44 % 30 km/h 0.0 mm High 31
12 Apr 38.2 °C 36 % 30 km/h 0.0 mm High 31
13 Apr 37.0 °C 40 % 34 km/h 0.0 mm High 34
14 Apr 38.0 °C 39 % 29 km/h 0.0 mm High 31
15 Apr 37.5 °C 43 % 32 km/h 1.2 mm High 23
16 Apr 36.8 °C 43 % 29 km/h 0.5 mm High 25
17 Apr 37.5 °C 43 % 32 km/h 0.5 mm High 28
18 Apr 37.9 °C 39 % 27 km/h 1.7 mm High 22
19 Apr 36.3 °C 45 % 30 km/h 1.5 mm Moderate 19
20 Apr 35.8 °C 42 % 28 km/h 0.6 mm High 23
21 Apr 35.7 °C 41 % 33 km/h 0.0 mm High 27
22 Apr 36.9 °C 40 % 34 km/h 0.0 mm High 30
23 Apr 37.2 °C 39 % 35 km/h 0.1 mm High 30
24 Apr 37.2 °C 40 % 28 km/h 0.0 mm High 30
25 Apr 37.0 °C 40 % 23 km/h 1.5 mm High 22
26 Apr 35.0 °C 47 % 24 km/h 0.3 mm High 22
27 Apr 35.8 °C 47 % 19 km/h 1.2 mm Moderate 16
28 Apr after 33.3 °C 54 % 30 km/h 3.0 mm Low 8

Before and after, from space

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

Before · 7 Mar 2026
After · 4 May 2026

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 14 April 2026 the air beside the fire reached 154 µg/m³ of PM2.5. That day averaged 60: 4.0 times the WHO daily guideline (15).

PM2.5 peak154 µg/m³
Days over the guideline46 days
PM10157 µg/m³
Optical depth1.67
1213141516171819202122232425262728293031123456789101112131415161718192021222324252627282930
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 · 515Every 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 Cambodia ›

Frequently asked questions

How long did the Siem Bouk fire last?
GWIS (Copernicus) dates it between 14 March 2026 and 27 April 2026: 45 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 2,997 hectares (30.0 km²). It is an estimate: official national figures may differ.
Which municipalities burned?
The fire only entered Siem Bouk (3,013 ha, 2.0 %).
What was the weather like?
During the fire the temperature reached 38.2 °C, humidity dropped to 34 % and gusts hit 45 km/h. The fire danger index (FWI) reached 34, class High.
Where does this data come from?
From the GWIS (Copernicus) burnt perimeter, NASA FIRMS VIIRS hotspots and the administrative boundaries of Cambodia (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

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 4.0 International (CC BY 4.0)). 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.