Thoen fire, 24 March 2025 เถิน · Thoen, Li, Mae Phrik
The fire started on 24 March 2025 in Thoen, Thailand, and satellites saw it burning for 7 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 2,863 hectares from heat detections, spread across 3 municipalities.
It is the 35th largest in Lampang Province since 2016 (of 216 with a page). Number 23 in Thailand in 2025, of 231.
The power measured by the satellite is low (17.3 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
- 2,863ha
- GWIS perimeter (Copernicus)
- Duration
- 7days
- 24 Mar 2025 – 30 Mar 2025
- Municipalities hit
- 3
- districts
- Started on
- 24 Mar
- 2025
- Heat detections
- 101
- in a single hotspot: 17 MW
- Danger at start
- 29
- High · FWI index
- Average daily power
- 43MW
- 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 27 days without rain (1 mm or more) when it started. Rain came after the fire: 5.6 mm on 1 Apr.
This area had burned before
80% of the perimeter overlaps earlier fires recorded since 2016: 1,060 ha in 2017, 523 ha in 2018, 1,125 ha in 2019, 205 ha in 2020, 582 ha in 2021, 858 ha in 2023, 764 ha in 2024. Part of it burned more than once, so the yearly figures add up to more than the 2,284 ha that had burned before.
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
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) |
|---|---|---|---|---|---|
| 24 Mar | 37.6 °C | 30 % | 20 km/h | 0.0 mm | High 29 |
| 25 Mar | 38.3 °C | 25 % | 30 km/h | 0.0 mm | High 34 |
| 26 Mar | 38.2 °C | 23 % | 34 km/h | 0.0 mm | High 37 |
| 27 Mar | 38.1 °C | 23 % | 32 km/h | 0.0 mm | High 37 |
| 28 Mar | 36.7 °C | 23 % | 28 km/h | 0.0 mm | High 37 |
| 29 Mar | 38.0 °C | 24 % | 28 km/h | 0.0 mm | High 36 |
| 30 Mar | 37.2 °C | 35 % | 31 km/h | 0.0 mm | High 34 |
| 31 Mar after | 35.0 °C | 47 % | 34 km/h | 0.7 mm | High 23 |
| 1 Apr after | 34.9 °C | 47 % | 30 km/h | 5.6 mm | Low 6 |
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 29 March 2025 the air beside the fire reached 122 µg/m³ of PM2.5. That day averaged 69: 4.6 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 · 101Every satellite heat detection, one by one, with time, satellite, power and coordinates.
| Date and time | Satellite | FRP (MW) | Lat | Lon |
|---|
Other fires nearby
- 45,311 haMae Phrik แม่พริก21 March 2026 · 35 days · 19 km away
- 12,196 haMae Phrik แม่พริก1 March 2024 · 19 days · 22 km away
- 21,139 haMae Phrik แม่พริก6 February 2019 · 33 days · 24 km away
- 28,586 haLi ลี้20 March 2026 · 24 days · 28 km away
- 18,226 haMae Phrik แม่พริก13 March 2025 · 19 days · 29 km away
- 12,046 haSam Ngao สามเงา18 March 2023 · 15 days · 37 km away
Frequently asked questions
- How long did the Thoen fire last?
- GWIS (Copernicus) dates it between 24 March 2025 and 30 March 2025: 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 2,863 hectares (28.6 km²). It is an estimate: official national figures may differ.
- Which municipalities burned?
- The fire entered 3 municipalities: Thoen (2,651 ha, 1.5 %); Li (150 ha, 0.1 %); Mae Phrik (78 ha, 0.1 %).
- What was the weather like?
- During the fire the temperature reached 38.3 °C, humidity dropped to 23 % and gusts hit 34 km/h. The fire danger index (FWI) reached 37, 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
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 from the perimeter: the VIIRS detections inside it did not change them. 101 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.
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.