Sop Moei fire, 17 March 2023 สบเมย · Sop Moei, Tha Song Yang
The fire started on 17 March 2023 in Sop Moei, Thailand, and satellites saw it burning for 10 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 1,765 hectares from heat detections, spread across 2 municipalities.
It is the 175th largest in Mae Hong Son Province since 2016 (of 387 with a page). Number 136 in Thailand in 2023, of 369.
Compare with…
- Burnt area
- 1,765ha
- GWIS perimeter (Copernicus)
- Duration
- 10days
- 17 Mar 2023 – 26 Mar 2023
- Municipalities hit
- 2
- districts
- Started on
- 17 Mar
- 2023
- Heat detections
- 69
- in a single hotspot: 65 MW
- Danger at start
- 4
- Very low · FWI index
- Average daily power
- 210MW
- 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 one day without rain (1 mm or more) when it started.
This area had burned before
94% of the perimeter overlaps earlier fires recorded since 2016: 1,158 ha in 2016, 477 ha in 2017, 376 ha in 2018, 828 ha in 2019, 728 ha in 2020, 813 ha in 2021, 225 ha in 2022. Part of it burned more than once, so the yearly figures add up to more than the 1,665 ha that had burned before.
- 826 ha Sop Moei fire, March 2019 12,470 ha in total; the hectares shown are those it shares with this fire
- 666 ha Sop Moei fire, March 2016 4,768 ha in total; the hectares shown are those it shares with this fire
- 20 ha Tha Song Yang fire, April 2018 1,584 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
-
1,770 ha reached on 17 Mar1.2 %
-
Tha Song Yang ท่าสองยาง4 ha0.0 %
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 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) |
|---|---|---|---|---|---|
| 17 Mar | 32.8 °C | 50 % | 26 km/h | 2.4 mm | Very low 4 |
| 18 Mar | 32.6 °C | 52 % | 30 km/h | 0.9 mm | Low 7 |
| 19 Mar | 32.1 °C | 56 % | 32 km/h | 1.0 mm | Low 8 |
| 20 Mar | 32.5 °C | 51 % | 35 km/h | 0.2 mm | Moderate 12 |
| 21 Mar | 33.5 °C | 47 % | 40 km/h | 0.3 mm | Moderate 15 |
| 22 Mar | 33.2 °C | 46 % | 42 km/h | 0.0 mm | Moderate 16 |
| 23 Mar | 33.6 °C | 43 % | 44 km/h | 0.5 mm | Moderate 18 |
| 24 Mar | 33.7 °C | 41 % | 36 km/h | 0.0 mm | Moderate 18 |
| 25 Mar | 33.5 °C | 44 % | 35 km/h | 0.2 mm | Moderate 18 |
| 26 Mar | 33.6 °C | 45 % | 34 km/h | 0.6 mm | Moderate 16 |
| 27 Mar after | 34.8 °C | 39 % | 38 km/h | 0.0 mm | Moderate 20 |
| 28 Mar after | 35.4 °C | 33 % | 41 km/h | 0.0 mm | High 24 |
| 29 Mar after | 33.3 °C | 47 % | 44 km/h | 0.4 mm | High 22 |
| 30 Mar after | 33.5 °C | 45 % | 36 km/h | 0.1 mm | High 21 |
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 20 March 2023 the air beside the fire reached 56 µg/m³ of PM2.5. That day averaged 38: 2.5 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 · 69Every satellite heat detection, one by one, with time, satellite, power and coordinates.
| Date and time | Satellite | FRP (MW) | Lat | Lon |
|---|
Other fires nearby
- 7,577 haTha Song Yang ท่าสองยาง6 April 2018 · 17 days · 7 km away
- 56,946 haSop Moei สบเมย21 March 2026 · 35 days · 8 km away
- 12,470 haSop Moei สบเมย20 March 2019 · 34 days · 13 km away
- 6,625 haSop Moei สบเมย7 March 2020 · 11 days · 18 km away
- 5,505 haSop Moei สบเมย14 March 2025 · 22 days · 30 km away
- 8,249 haMae Sariang แม่สะเรียง20 February 2021 · 20 days · 39 km away
Frequently asked questions
- How long did the Sop Moei fire last?
- According to the heat detections seen by satellite inside the perimeter, it burned from 17 March 2023 to 26 March 2023 (10 days). The perimeter dates it from 17 March 2023 to 20 March 2023.
- How much area did it burn?
- The perimeter GWIS (Copernicus) rebuilt from heat detections is 1,765 hectares (17.6 km²). It is an estimate: official national figures may differ.
- Which municipalities burned?
- The fire entered 2 municipalities: Sop Moei (1,770 ha, 1.2 %); Tha Song Yang (4 ha, 0.0 %).
- What was the weather like?
- During the fire the temperature reached 32.8 °C, humidity dropped to 50 % and gusts hit 35 km/h. The fire danger index (FWI) reached 12, 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: 20 March 2023 → 26 March 2023.
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 17 March 2023 to 20 March 2023. 69 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.