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Den Chai fire, 19 March 2023 เด่นชัย · Den Chai, Tha Pla

Out · last detection 15 Apr 2023, 19:28 UTC

The fire started on 19 March 2023 in Den Chai, Thailand, and satellites saw it burning for 27 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 3,582 hectares from heat detections, spread across 2 municipalities.

It is the 11th largest in Phrae Province since 2016 (of 116 with a page). Number 39 in Thailand in 2023, of 369.

The power measured by the satellite is low (12.9 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: Den Chai · 2016Den Chai · 2019Sung Men · 2019Den Chai · 2019

Burnt area
3,582ha
GWIS perimeter (Copernicus)
Duration
27days
19 Mar 2023 – 14 Apr 2023
Municipalities hit
2
districts
Started on
19 Mar
2023
Heat detections
147
in a single hotspot: 13 MW
Danger at start
24
High · FWI index
Average daily power
18MW
detected power per day, on average

Where it burned

HOTSPOTS BY DAY 19 Mar14 Apr
15 Apr 2023

How it evolved, day by day

19 Mar 2023 · 13 MW · 2 20 Mar 2023 · 2 MW · 1 21 Mar 2023 · 11 MW · 3 22 Mar 2023 · 14 MW · 4 23 Mar 2023 · 3 MW · 2 24 Mar 2023 · 8 MW · 5 25 Mar 2023 · 45 MW · 10 26 Mar 2023 · 54 MW · 21 27 Mar 2023 · 25 MW · 6 28 Mar 2023 · 14 MW · 4 29 Mar 2023 · 11 MW · 3 30 Mar 2023 · 13 MW · 5 31 Mar 2023 · 18 MW · 7 2 Apr 2023 · 5 MW · 2 3 Apr 2023 · 1 MW · 1 4 Apr 2023 · 13 MW · 5 5 Apr 2023 · 91 MW · 21 6 Apr 2023 · 51 MW · 23 7 Apr 2023 · 36 MW · 13 10 Apr 2023 · 2 MW · 1 11 Apr 2023 · 3 MW · 1 12 Apr 2023 · 2 MW · 1 13 Apr 2023 · 2 MW · 1 14 Apr 2023 · 12 MW · 4 15 Apr 2023 · 5 MW · 1
19 Mar 23 Mar 27 Mar 31 Mar 5 Apr 11 Apr 15 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

38°high
36km/h · peak gust
25%lowest humidity

It had gone 2 days without rain (1 mm or more) when it started.

This area had burned before

86% of the perimeter overlaps earlier fires recorded since 2016: 3,043 ha in 2016, 170 ha in 2017, 398 ha in 2018, 3,059 ha in 2019, 463 ha in 2020, 864 ha in 2021. Part of it burned more than once, so the yearly figures add up to more than the 3,067 ha that had burned before.

How big is it?

10 km
It burned the equivalent of 2.3% of the area of London (36 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

  1. Den Chai เด่นชัย where it started
    2,494 ha reached on 19 Mar
    4.6 %
  2. Tha Pla ท่าปลา
    1,108 ha reached on 30 Mar
    0.6 %

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 area< 0.1 ha
Residents< 20

Inside the perimeter there was no noticeable built-up land and almost nobody lived there (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)
19 Mar 35.6 °C 38 % 32 km/h 0.4 mm High 24
20 Mar 36.0 °C 35 % 28 km/h 0.1 mm High 25
21 Mar 36.6 °C 32 % 31 km/h 0.4 mm High 28
22 Mar 37.1 °C 29 % 32 km/h 0.0 mm High 30
23 Mar 37.9 °C 26 % 36 km/h 0.0 mm High 34
24 Mar 37.8 °C 27 % 28 km/h 0.0 mm High 31
25 Mar 37.5 °C 25 % 29 km/h 0.0 mm High 32
26 Mar 36.8 °C 31 % 30 km/h 0.0 mm High 33
27 Mar 37.6 °C 27 % 32 km/h 0.0 mm High 34
28 Mar 36.2 °C 37 % 34 km/h 0.0 mm High 33
29 Mar 35.8 °C 35 % 30 km/h 0.0 mm High 32
30 Mar 35.8 °C 35 % 29 km/h 0.0 mm High 32
31 Mar 36.2 °C 35 % 27 km/h 0.0 mm High 31
1 Apr 35.6 °C 39 % 31 km/h 0.0 mm High 31
2 Apr 36.9 °C 30 % 33 km/h 0.0 mm High 33
3 Apr 37.3 °C 25 % 31 km/h 0.0 mm High 36
4 Apr 37.1 °C 29 % 28 km/h 0.0 mm High 35
5 Apr 37.0 °C 28 % 23 km/h 0.0 mm High 33
6 Apr 37.5 °C 31 % 25 km/h 0.0 mm High 34
7 Apr 37.7 °C 30 % 27 km/h 0.0 mm High 35
8 Apr 37.0 °C 39 % 27 km/h 0.0 mm High 32
9 Apr 36.0 °C 43 % 35 km/h 0.1 mm High 32
10 Apr 38.3 °C 32 % 30 km/h 0.0 mm High 32
11 Apr 38.4 °C 34 % 31 km/h 0.0 mm High 33
12 Apr 38.8 °C 32 % 29 km/h 0.0 mm High 32
13 Apr 38.3 °C 37 % 26 km/h 0.0 mm High 32
14 Apr 39.2 °C 32 % 27 km/h 0.0 mm High 32
15 Apr after 38.9 °C 34 % 30 km/h 0.0 mm High 32
16 Apr after 37.6 °C 38 % 34 km/h 0.0 mm High 35
17 Apr after 38.4 °C 35 % 33 km/h 0.0 mm High 37

Before and after, from space

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

Before · 12 Mar 2023
After · 21 Apr 2023

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 6 April 2023 the air beside the fire reached 71 µg/m³ of PM2.5. That day averaged 50: 3.3 times the WHO daily guideline (15).

PM2.5 peak71 µg/m³
Days over the guideline22 days
PM10102 µg/m³
Optical depth1.56
17181920212223242526272829303112345678910
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 · 147Every 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 Thailand ›

Frequently asked questions

How long did the Den Chai fire last?
According to the heat detections seen by satellite inside the perimeter, it burned from 19 March 2023 to 14 April 2023 (27 days). The perimeter dates it from 19 March 2023 to 7 April 2023.
How much area did it burn?
The perimeter GWIS (Copernicus) rebuilt from heat detections is 3,582 hectares (35.8 km²). It is an estimate: official national figures may differ.
Which municipalities burned?
The fire entered 2 municipalities: Den Chai (2,494 ha, 4.6 %); Tha Pla (1,108 ha, 0.6 %).
What was the weather like?
During the fire the temperature reached 37.9 °C, humidity dropped to 25 % and gusts hit 36 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 · Emergency number and official warnings ›

Satellite cross-check

History of this page · 1 Changes in area, dates, name, official record or merged pages, compared every night since 24 October 2026.
  1. Last day with fire: 7 April 2023 → 14 April 2023.

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.

Report an error
What do you think is wrong?

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; 2 polygons grouped in this page.
  • Dates adjusted with the VIIRS detections inside the perimeter, which said 19 March 2023 to 7 April 2023. 147 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.