Dan Sai fire, 19 March 2021 ด่านซ้าย · Dan Sai, Lom Kao
The fire started on 19 March 2021 in Dan Sai, Thailand, and satellites saw it burning for 13 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 1,398 hectares from heat detections, spread across 2 municipalities.
It is the 67th largest in Loei Province since 2016 (of 113 with a page). Number 92 in Thailand in 2021, of 187.
Compare with…
- Burnt area
- 1,398ha
- GWIS perimeter (Copernicus)
- Duration
- 13days
- 19 Mar 2021 – 31 Mar 2021
- Municipalities hit
- 2
- districts
- Started on
- 19 Mar
- 2021
- Heat detections
- 49
- in a single hotspot: 32 MW
- Danger at start
- 12
- Moderate · FWI index
- Average daily power
- 50MW
- detected power per day, on average
Where it burned
How it evolved, day by day
Fire radiative power detected each day, in megawatts, and number of hotspots. The magenta bar marks the peak day.
The weather it burned in
It had gone 0 days without rain (1 mm or more) when it started. Rain came after the fire: 2.9 mm on 26 Mar.
This area had burned before
99% of the perimeter overlaps earlier fires recorded since 2016: 1,352 ha in 2016, 1,301 ha in 2017, 636 ha in 2018, 1,368 ha in 2019, 38 ha in 2020. Part of it burned more than once, so the yearly figures add up to more than the 1,391 ha that had burned before.
- 1,155 ha Lom Kao fire, April 2019 1,554 ha in total; the hectares shown are those it shares with this fire
- 1,017 ha Lom Kao fire, April 2016 1,471 ha in total; the hectares shown are those it shares with this fire
- 980 ha Dan Sai fire, April 2017 1,695 ha in total; the hectares shown are those it shares with this fire
- 324 ha Lom Kao fire, April 2018 2,049 ha in total; the hectares shown are those it shares with this fire
- 321 ha Lom Kao fire, April 2017 1,348 ha in total; the hectares shown are those it shares with this fire
How big is it?
London boundary: geoBoundaries · Office for National Statistics (Open Government Licence v3.0).
Bangkok boundary: geoBoundaries · OpenStreetMap, Wambacher · © OpenStreetMap contributors (ODbL 1.0).
Paris boundary: geoBoundaries · Institut national de l'information géographique et forestière (IGN-F) (Etalab Open License 2.0).
Madrid boundary: geoBoundaries · Open Data ESRI, IGN Central Registry of Cartography Area (CC BY 4.0).
This compares size, not location: both shapes are at the same scale, north up, centred on each other.
What happened to each town
-
1,243 ha reached on 19 Mar0.9 %
-
Lom Kao หล่มเก่า162 ha reached on 20 Mar0.2 %
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 2020Inside the perimeter there was no noticeable built-up land and almost nobody lived there (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) |
|---|---|---|---|---|---|
| 19 Mar | 35.1 °C | 51 % | 23 km/h | 0.0 mm | Moderate 12 |
| 20 Mar | 35.9 °C | 47 % | 24 km/h | 0.3 mm | Moderate 16 |
| 21 Mar | 35.3 °C | 53 % | 26 km/h | 12.1 mm | Very low 2 |
| 22 Mar | 30.2 °C | 52 % | 44 km/h | 1.5 mm | Low 6 |
| 23 Mar | 31.3 °C | 51 % | 28 km/h | 0.0 mm | Low 9 |
| 24 Mar | 32.9 °C | 50 % | 26 km/h | 0.0 mm | Moderate 12 |
| 25 Mar | 34.0 °C | 51 % | 22 km/h | 0.3 mm | Moderate 12 |
| 26 Mar | 35.5 °C | 48 % | 28 km/h | 2.9 mm | Very low 5 |
Before and after, from space
Drag the line to compare the same ground before the fire and after it.
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 · 49Every satellite heat detection, one by one, with time, satellite, power and coordinates.
| Date and time | Satellite | FRP (MW) | Lat | Lon |
|---|
Other fires nearby
- 7,219 haLom Kao หล่มเก่า8 April 2026 · 14 days · 12 km away
- 6,404 haDan Sai ด่านซ้ายMarch 2016 · 19 days · 15 km away
- 4,640 haDan Sai ด่านซ้าย5 March 2019 · 19 days · 17 km away
- 7,064 haLom Kao หล่มเก่าFebruary 2021 · 10 days · 19 km away
- 6,306 haPhu Ruea ภูเรือ3 April 2026 · 13 days · 28 km away
- 9,284 haLom Sak หล่มสัก28 March 2026 · 21 days · 35 km away
Frequently asked questions
- How long did the Dan Sai fire last?
- According to the heat detections seen by satellite inside the perimeter, it burned from 19 March 2021 to 31 March 2021 (13 days). The perimeter dates it from 19 March 2021 to 25 March 2021.
- How much area did it burn?
- The perimeter GWIS (Copernicus) rebuilt from heat detections is 1,398 hectares (14.0 km²). It is an estimate: official national figures may differ.
- Which municipalities burned?
- The fire entered 2 municipalities: Dan Sai (1,243 ha, 0.9 %); Lom Kao (162 ha, 0.2 %).
- What was the weather like?
- During the fire the temperature reached 35.9 °C, humidity dropped to 47 % and gusts hit 44 km/h. The fire danger index (FWI) reached 16, class Moderate.
- 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.
- Last day with fire: 25 March 2021 → 31 March 2021.
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
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 19 March 2021 to 25 March 2021. 49 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.
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.