How long did the Khun Yuam fire last?

GWIS (Copernicus) dates it between 20 March 2019 and 26 March 2019: 7 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 3,087 hectares (30.9 km²). It is an estimate: official national figures may differ.

Which municipalities burned?

The fire only entered Khun Yuam (3,106 ha, 1.9 %).

What was the weather like?

During the fire the temperature reached 39.0 °C, humidity dropped to 20 % and gusts hit 38 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 Thailand (geoBoundaries). It is not an official report.

TH · Thailand · 2019-03-20 → 2019-03-26

Khun Yuam fire, 20 March 2019 ขุนยวม · Khun Yuam

Out · last detection 26 Mar 2019, 18:54 UTC

The fire started on 20 March 2019 in Khun Yuam, Thailand, and satellites saw it burning for 7 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 3,087 hectares from heat detections, spread across a single municipality.

It is the 82th largest in Mae Hong Son Province since 2016 (of 387 with a page). Number 48 in Thailand in 2019, of 385.

The power measured by the satellite is low (27.8 MW in the strongest hotspot), more typical of grass or stubble burning, or a slow surface fire, than of a large crown fire.

Compare with…

Suggestions: Khun Yuam · 2016 Mueang Mae Hong Son · 2025 Mueang Mae Hong Son · 2026 Mese · 2026

Burnt area: 3,087ha; GWIS perimeter (Copernicus)
Duration: 7days; 20 Mar 2019 – 26 Mar 2019
Municipalities hit: 1; districts
Started on: 20 Mar; 2019
Heat detections: 100; in a single hotspot: 28 MW
Danger at start: 37; High · FWI index
Average daily power: 50MW; detected power per day, on average

HOTSPOTS BY DAY 20 Mar26 Mar

Play back 26 Mar 2019

How it evolved, day by day

20 Mar 21 Mar 22 Mar 23 Mar 24 Mar 25 Mar 26 Mar

Fire radiative power detected each day, in megawatts, and number of hotspots. The magenta bar marks the peak day.

The weather it burned in

39°high

38km/h · peak gust

20%lowest humidity

It had gone more than two months without rain (1 mm or more) when it started.

This area had burned before

66% of the perimeter overlaps earlier fires recorded since 2016: 1,362 ha in 2016, 797 ha in 2017, 296 ha in 2018. Part of it burned more than once, so the yearly figures add up to more than the 2,028 ha that had burned before.

1,260 ha Khun Yuam fire, March 2016 1,992 ha in total; the hectares shown are those it shares with this fire

How big is it?

It burned the equivalent of 1.9% 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

Khun Yuam ขุนยวม where it started

3,106 ha reached on 20 Mar

1.9 %

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 2020

Built-up area1.7 ha

Residents≈ 200

Inside the perimeter there were about 1.7 hectares of built-up land and about 200 residents (GHSL 2020, 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.

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)
13 Mar	36.3 °C	23 %	24 km/h	0.0 mm	High 37
14 Mar	36.8 °C	24 %	27 km/h	0.0 mm	Very high 39
15 Mar	36.3 °C	31 %	26 km/h	0.0 mm	High 36
16 Mar	37.4 °C	27 %	30 km/h	0.0 mm	High 36
17 Mar	37.4 °C	22 %	30 km/h	0.0 mm	High 36
18 Mar	37.5 °C	26 %	36 km/h	0.0 mm	Very high 39
19 Mar	37.1 °C	24 %	36 km/h	0.0 mm	Very high 40
20 Mar	37.1 °C	25 %	38 km/h	0.0 mm	Very high 41
21 Mar	37.2 °C	21 %	31 km/h	0.0 mm	Very high 38
22 Mar	37.1 °C	23 %	26 km/h	0.0 mm	High 36
23 Mar	37.8 °C	21 %	32 km/h	0.0 mm	Very high 40
24 Mar	38.3 °C	20 %	33 km/h	0.0 mm	Very high 40
25 Mar	38.6 °C	22 %	32 km/h	0.0 mm	Very high 41
26 Mar	39.0 °C	21 %	31 km/h	0.0 mm	Very high 41
27 Mar after	36.4 °C	34 %	39 km/h	0.0 mm	Very high 39
28 Mar after	36.8 °C	25 %	35 km/h	0.0 mm	Very high 38
29 Mar after	37.7 °C	21 %	27 km/h	0.0 mm	High 38
30 Mar after	37.9 °C	24 %	30 km/h	0.0 mm	Very high 40
31 Mar after	37.8 °C	21 %	35 km/h	0.0 mm	Very high 41
1 Apr after	38.1 °C	18 %	36 km/h	0.0 mm	Very high 43
2 Apr after	38.8 °C	21 %	32 km/h	0.0 mm	Very high 42
3 Apr after	37.0 °C	30 %	33 km/h	0.4 mm	Very high 40
4 Apr after	38.4 °C	22 %	31 km/h	0.0 mm	Very high 39
5 Apr after	39.0 °C	21 %	31 km/h	0.0 mm	Very high 41

Before and after, from space

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

↔

Before · 13 Mar 2019

After · 2 Apr 2019

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 · 100Every 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 Thailand ›

Frequently asked questions

How long did the Khun Yuam fire last?: GWIS (Copernicus) dates it between 20 March 2019 and 26 March 2019: 7 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 3,087 hectares (30.9 km²). It is an estimate: official national figures may differ.
Which municipalities burned?: The fire only entered Khun Yuam (3,106 ha, 1.9 %).
What was the weather like?: During the fire the temperature reached 39.0 °C, humidity dropped to 20 % and gusts hit 38 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 Thailand (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.

Emergency number: 199 · 191 · Emergency number and official warnings ›

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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We will only use your email to reply about this report. Privacy. This is not an emergency service: if there is a fire now, call 199 · 191.

How we know this

Perimeter: GWIS (Copernicus), rebuilt from heat detections rather than mapped on imagery.
Dates from the perimeter: the VIIRS detections inside it did not change them. 100 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 2020, 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