Lan Sak fire, 13 April 2026 ลานสัก · Lan Sak
The fire started on 13 April 2026 in Lan Sak, Thailand, and satellites saw it burning for 7 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 1,172 hectares from heat detections, spread across a single municipality.
It is the 60th largest in Uthai Thani Province since 2016 (of 73 with a page). Number 559 in Thailand in 2026, of 689.
The power measured by the satellite is low (19.8 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…
- Burnt area
- 1,172ha
- GWIS perimeter (Copernicus)
- Duration
- 7days
- 13 Apr 2026 – 19 Apr 2026
- Municipalities hit
- 1
- districts
- Started on
- 13 Apr
- 2026
- Heat detections
- 21
- in a single hotspot: 20 MW
- Danger at start
- 22
- High · FWI index
- Average daily power
- 35MW
- 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 12 days without rain (1 mm or more) when it started. Rain came after the fire: 2.1 mm on 24 Apr.
This area had burned before
100% of the perimeter overlaps earlier fires recorded since 2016: 953 ha in 2016, 683 ha in 2017, 702 ha in 2018, 641 ha in 2019, 200 ha in 2020, 102 ha in 2021, 859 ha in 2023, 626 ha in 2024, 132 ha in 2025. Part of it burned more than once, so the yearly figures add up to more than the 1,170 ha that had burned before.
- 641 ha Lan Sak fire, March 2019 20,476 ha in total; the hectares shown are those it shares with this fire
- 119 ha Lan Sak fire, March 2023 1,661 ha in total; the hectares shown are those it shares with this fire
- 102 ha Lan Sak fire, February 2021 1,415 ha in total; the hectares shown are those it shares with this fire
- 97 ha Lan Sak fire, March 2024 1,370 ha in total; the hectares shown are those it shares with this fire
- 86 ha Lan Sak fire, March 2024 3,423 ha in total; the hectares shown are those it shares with this fire
- 3 ha Lan Sak fire, April 2023 2,453 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
-
1,179 ha reached on 14 Apr0.8 %
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 2025Inside the perimeter there were about 0.23 hectares of 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) |
|---|---|---|---|---|---|
| 3 Apr | 39.2 °C | 32 % | 30 km/h | 0.0 mm | High 22 |
| 4 Apr | 38.2 °C | 36 % | 27 km/h | 0.0 mm | High 22 |
| 5 Apr | 38.4 °C | 35 % | 27 km/h | 0.0 mm | High 23 |
| 6 Apr | 38.4 °C | 35 % | 26 km/h | 0.0 mm | High 24 |
| 7 Apr | 38.9 °C | 34 % | 29 km/h | 0.0 mm | High 25 |
| 8 Apr | 39.6 °C | 31 % | 24 km/h | 0.0 mm | High 25 |
| 9 Apr | 38.8 °C | 32 % | 26 km/h | 0.0 mm | High 26 |
| 10 Apr | 39.4 °C | 28 % | 25 km/h | 0.0 mm | High 28 |
| 11 Apr | 38.4 °C | 36 % | 34 km/h | 0.0 mm | High 29 |
| 12 Apr | 39.1 °C | 32 % | 26 km/h | 0.0 mm | High 29 |
| 13 Apr | 38.9 °C | 30 % | 23 km/h | 0.0 mm | High 29 |
| 14 Apr | 40.1 °C | 25 % | 25 km/h | 0.0 mm | High 31 |
| 15 Apr | 39.5 °C | 29 % | 24 km/h | 0.0 mm | High 32 |
| 16 Apr | 39.9 °C | 29 % | 30 km/h | 0.0 mm | High 34 |
| 17 Apr | 39.0 °C | 31 % | 29 km/h | 0.0 mm | High 34 |
| 18 Apr | 39.1 °C | 33 % | 25 km/h | 0.0 mm | High 33 |
| 19 Apr | 38.8 °C | 33 % | 22 km/h | 0.0 mm | High 33 |
| 20 Apr after | 40.2 °C | 28 % | 22 km/h | 0.0 mm | High 33 |
| 21 Apr after | 39.6 °C | 32 % | 21 km/h | 0.0 mm | High 33 |
| 22 Apr after | 38.8 °C | 39 % | 21 km/h | 0.0 mm | High 31 |
| 23 Apr after | 37.8 °C | 40 % | 20 km/h | 0.1 mm | High 29 |
| 24 Apr after | 37.0 °C | 48 % | 26 km/h | 2.1 mm | Low 11 |
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.
The smoke
CAMS · CopernicusOn 12 April 2026 the air beside the fire reached 77 µg/m³ of PM2.5. That day averaged 47: 3.2 times the WHO daily guideline (15).
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 · 21Every satellite heat detection, one by one, with time, satellite, power and coordinates.
| Date and time | Satellite | FRP (MW) | Lat | Lon |
|---|
Other fires nearby
- 20,476 haLan Sak ลานสัก3 March 2019 · 15 days · 5 km away
- 57,928 haMae Poen แม่เปิน23 March 2026 · 31 days · 8 km away
- 6,804 haLan Sak ลานสัก19 February 2020 · 14 days · 14 km away
- 6,266 haLan Sak ลานสัก13 April 2026 · 10 days · 15 km away
- 6,174 haLan Sak ลานสัก8 February 2020 · 20 days · 27 km away
- 15,759 haMae Wong แม่วงก์March 2019 · 15 days · 37 km away
Frequently asked questions
- How long did the Lan Sak fire last?
- According to the heat detections seen by satellite inside the perimeter, it burned from 13 April 2026 to 19 April 2026 (7 days). The perimeter dates it from 14 April 2026 to 18 April 2026.
- How much area did it burn?
- The perimeter GWIS (Copernicus) rebuilt from heat detections is 1,172 hectares (11.7 km²). It is an estimate: official national figures may differ.
- Which municipalities burned?
- The fire only entered Lan Sak (1,179 ha, 0.8 %).
- What was the weather like?
- During the fire the temperature reached 40.1 °C, humidity dropped to 25 % and gusts hit 34 km/h. The fire danger index (FWI) reached 34, 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 · 2 Changes in area, dates, name, official record or merged pages, compared every night since 24 October 2026.
- Last day with fire: 18 April 2026 → 19 April 2026.
- Start date: 14 April 2026 → 13 April 2026.
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 14 April 2026 to 18 April 2026. 21 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.
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.