How long did the Thoeng fire last?

GWIS (Copernicus) dates it between 11 April 2023 and 19 April 2023: 9 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 1,329 hectares (13.3 km²). It is an estimate: official national figures may differ.

Which municipalities burned?

The fire entered 2 municipalities: Thoeng (1,284 ha, 1.5 %); Khun Tan (53 ha, 0.2 %).

What was the weather like?

During the fire the temperature reached 37.3 °C, humidity dropped to 26 % and gusts hit 42 km/h. The fire danger index (FWI) reached 36, class 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 · 2023-04-11 → 2023-04-19

Thoeng fire, April 2023 Thoeng, Khun Tan

Out · last detection 19 Apr 2023, 18:12 UTC

The fire started on 11 April 2023 in Thoeng, Thailand, and satellites saw it burning for 9 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 1,329 hectares from heat detections, spread across 2 municipalities.

It is the 197th largest in Chiang Rai Province since 2016 (of 303 with a page). Number 317 in Thailand in 2023, of 500.

Burnt area: 1,329ha; GWIS perimeter (Copernicus)
Duration: 9days; 11 Apr 2023 – 19 Apr 2023
Municipalities hit: 2; districts
Started on: 11 Apr; 2023
Heat detections: 87; in a single hotspot: 46 MW
Danger at start: 32; High · FWI index
Energy released: 449MW; sum of detected power

Play back 19 Apr 2023

HOTSPOTS BY DAY 11 Apr19 Apr

How it evolved, day by day

1112131415161719

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

42km/h · peak gust

26%lowest humidity

It had gone 15 days without rain (1 mm or more) when it started. Rain came after the fire: 1.3 mm on 26 Apr.

This area had burned before

71% of the perimeter overlaps earlier fires recorded since 2016: 448 ha in 2016, 38 ha in 2018, 844 ha in 2019, 223 ha in 2020, 221 ha in 2021. Part of it burned more than once, so the yearly figures add up to more than the 941 ha that had burned before.

446 ha Khun Tan fire, April 2016 1,926 ha in total; the hectares shown are those it shares with this fire

What happened to each town

Thoeng where it started

1,284 ha reached on 5 Apr

1.5 %
Khun Tan

53 ha reached on 9 Apr

0.2 %

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)
29 Mar	33.5 °C	28 %	36 km/h	0.0 mm	High 32
30 Mar	33.1 °C	33 %	28 km/h	0.0 mm	High 28
31 Mar	33.1 °C	34 %	24 km/h	0.0 mm	High 27
1 Apr	34.0 °C	34 %	32 km/h	0.0 mm	High 30
2 Apr	34.7 °C	28 %	42 km/h	0.0 mm	High 34
3 Apr	33.0 °C	30 %	39 km/h	0.0 mm	High 34
4 Apr	33.7 °C	30 %	33 km/h	0.0 mm	High 32
5 Apr	33.7 °C	26 %	27 km/h	0.0 mm	High 30
6 Apr	34.1 °C	30 %	23 km/h	0.0 mm	High 31
7 Apr	34.3 °C	34 %	28 km/h	0.0 mm	High 32
8 Apr	34.6 °C	39 %	32 km/h	0.0 mm	High 30
9 Apr	35.4 °C	35 %	41 km/h	0.0 mm	High 34
10 Apr	36.1 °C	30 %	31 km/h	0.0 mm	High 32
11 Apr	36.1 °C	30 %	25 km/h	0.0 mm	High 31
12 Apr	36.1 °C	28 %	24 km/h	0.0 mm	High 31
13 Apr	36.3 °C	34 %	27 km/h	0.0 mm	High 32
14 Apr	37.3 °C	28 %	25 km/h	0.0 mm	High 33
15 Apr	36.4 °C	28 %	22 km/h	0.0 mm	High 33
16 Apr	37.0 °C	33 %	36 km/h	0.0 mm	High 36
17 Apr	35.6 °C	36 %	34 km/h	0.0 mm	High 36
18 Apr	36.8 °C	33 %	28 km/h	0.0 mm	High 34
19 Apr	37.0 °C	30 %	28 km/h	0.0 mm	High 34
20 Apr after	36.3 °C	32 %	28 km/h	0.0 mm	High 34
21 Apr after	35.8 °C	33 %	29 km/h	0.0 mm	High 35
22 Apr after	35.2 °C	35 %	29 km/h	0.4 mm	High 35
23 Apr after	36.9 °C	29 %	29 km/h	0.0 mm	High 36
24 Apr after	33.7 °C	38 %	31 km/h	0.0 mm	High 34
25 Apr after	35.9 °C	30 %	22 km/h	0.0 mm	High 31
26 Apr after	32.6 °C	44 %	44 km/h	1.3 mm	High 24

Before and after, from space

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

↔

Before · 4 Apr 2023

After · 26 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 12 April 2023 the air beside the fire reached 83 µg/m³ of PM2.5. That day averaged 66: 4.4 times the WHO daily guideline (15).

PM2.5 peak83 µg/m³

Days over the guideline14 days

PM10118 µg/m³

Optical depth1.67

WHO 15

910111213141516171819202122

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 · 87Every 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 Thoeng fire last?: GWIS (Copernicus) dates it between 11 April 2023 and 19 April 2023: 9 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 1,329 hectares (13.3 km²). It is an estimate: official national figures may differ.
Which municipalities burned?: The fire entered 2 municipalities: Thoeng (1,284 ha, 1.5 %); Khun Tan (53 ha, 0.2 %).
What was the weather like?: During the fire the temperature reached 37.3 °C, humidity dropped to 26 % and gusts hit 42 km/h. The fire danger index (FWI) reached 36, class 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

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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What really happened?

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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.

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