How long did the Nambak fire last?

According to the heat detections seen by satellite inside the perimeter, it burned from 2 April 2023 to 20 April 2023 (19 days). The perimeter dates it from 4 April 2023 to 13 April 2023.

How much area did it burn?

The perimeter GWIS (Copernicus) rebuilt from heat detections is 3,121 hectares (31.2 km²). It is an estimate: official national figures may differ.

Which municipalities burned?

The fire only entered Nambak (3,138 ha, 1.6 %).

What was the weather like?

During the fire the temperature reached 40.2 °C, humidity dropped to 25 % and gusts hit 41 km/h. The fire danger index (FWI) reached 37, 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 · 2023-04-02 → 2023-04-20

Nambak fire, 2 April 2023 Nambak

Out · last detection 20 Apr 2023, 07:04 UTC

The fire started on 2 April 2023 in Nambak, Laos, and satellites saw it burning for 19 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 3,121 hectares from heat detections, spread across a single municipality.

It is the 120th largest in Luang Prabang since 2016 (of 295 with a page). Number 104 in Laos in 2023, of 239.

Compare with…

Suggestions: Nambak · 2017 Ngoi · 2018 Park Ou · 2026 Nambak · 2026

Burnt area: 3,121ha; GWIS perimeter (Copernicus)
Duration: 19days; 2 Apr 2023 – 20 Apr 2023
Municipalities hit: 1; districts
Started on: 2 Apr; 2023
Heat detections: 150; in a single hotspot: 556 MW
Danger at start: 21; Moderate · FWI index
Average daily power: 208MW; detected power per day, on average

HOTSPOTS BY DAY 2 Apr20 Apr

Play back 20 Apr 2023

How it evolved, day by day

2 Apr 5 Apr 6 Apr 8 Apr 11 Apr 14 Apr 17 Apr 20 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

40°high

41km/h · peak gust

25%lowest humidity

It had gone 2 days without rain (1 mm or more) when it started. Rain came after the fire: 1.8 mm on 25 Apr.

This area had burned before

85% of the perimeter overlaps earlier fires recorded since 2016: 1,040 ha in 2017, 1,395 ha in 2018, 916 ha in 2019, 678 ha in 2020, 625 ha in 2021. Part of it burned more than once, so the yearly figures add up to more than the 2,664 ha that had burned before.

1,040 ha Nambak fire, April 2017 2,380 ha in total; the hectares shown are those it shares with this fire

How big is it?

It burned the equivalent of 2% of the area of London (31 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

Nambak where it started

3,138 ha reached on 2 Apr

1.6 %

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 area1.2 ha

Residents≈ 450

Inside the perimeter there were about 1.2 hectares of built-up land and about 450 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)
2 Apr	35.6 °C	37 %	41 km/h	0.0 mm	Moderate 21
3 Apr	35.8 °C	33 %	40 km/h	0.0 mm	High 23
4 Apr	36.1 °C	31 %	40 km/h	0.0 mm	High 25
5 Apr	36.4 °C	28 %	32 km/h	0.0 mm	High 25
6 Apr	36.9 °C	31 %	19 km/h	0.0 mm	High 24
7 Apr	35.7 °C	39 %	28 km/h	0.0 mm	High 24
8 Apr	32.5 °C	56 %	36 km/h	1.3 mm	Low 10
9 Apr	34.0 °C	58 %	38 km/h	0.5 mm	Moderate 13
10 Apr	37.3 °C	35 %	31 km/h	0.0 mm	High 23
11 Apr	38.1 °C	34 %	26 km/h	0.0 mm	High 23
12 Apr	37.7 °C	34 %	28 km/h	0.0 mm	High 25
13 Apr	37.5 °C	38 %	29 km/h	0.0 mm	High 26
14 Apr	38.7 °C	36 %	28 km/h	0.0 mm	High 26
15 Apr	37.9 °C	36 %	34 km/h	0.0 mm	High 31
16 Apr	36.6 °C	50 %	35 km/h	0.3 mm	High 23
17 Apr	37.3 °C	38 %	36 km/h	0.0 mm	High 27
18 Apr	39.7 °C	30 %	38 km/h	0.0 mm	High 33
19 Apr	40.2 °C	25 %	36 km/h	0.0 mm	High 37
20 Apr	40.1 °C	29 %	34 km/h	0.0 mm	High 36
21 Apr after	39.8 °C	29 %	36 km/h	0.0 mm	High 38
22 Apr after	37.1 °C	40 %	34 km/h	0.4 mm	High 32
23 Apr after	38.9 °C	30 %	32 km/h	0.4 mm	High 32
24 Apr after	36.9 °C	37 %	37 km/h	0.1 mm	High 31
25 Apr after	37.4 °C	40 %	28 km/h	1.8 mm	Moderate 17

Before and after, from space

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

↔

Before · 26 Mar 2023

After · 27 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.

The smoke

CAMS · Copernicus

On 7 April 2023 the air beside the fire reached 2,667 µg/m³ of PM2.5. That day averaged 1,294: 86 times the WHO daily guideline (15).

PM2.5 peak2,667 µg/m³

Days over the guideline24 days

PM102,980 µg/m³

Optical depth11.34

WHO 15

311234567891011121314151617181920212223

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 · 150Every 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 Nambak fire last?: According to the heat detections seen by satellite inside the perimeter, it burned from 2 April 2023 to 20 April 2023 (19 days). The perimeter dates it from 4 April 2023 to 13 April 2023.
How much area did it burn?: The perimeter GWIS (Copernicus) rebuilt from heat detections is 3,121 hectares (31.2 km²). It is an estimate: official national figures may differ.
Which municipalities burned?: The fire only entered Nambak (3,138 ha, 1.6 %).
What was the weather like?: During the fire the temperature reached 40.2 °C, humidity dropped to 25 % and gusts hit 41 km/h. The fire danger index (FWI) reached 37, 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 ↗

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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What really happened?

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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 4 April 2023 to 13 April 2023. 150 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