Pai fire, 26 April 2024 Pai
The fire started on 26 April 2024 in Pai, Thailand, and satellites saw it burning for 7 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 2,539 hectares from heat detections, spread across a single municipality.
It is the 198th largest in Mae Hong Son Province since 2016 (of 668 with a page). Number 72 in Thailand in 2024, of 350.
The power measured by the satellite is low (11.0 MW in the strongest hotspot), more typical of grass or stubble burning, or a slow surface fire, than of a large crown fire.
- Burnt area
- 2,539ha
- GWIS perimeter (Copernicus)
- Duration
- 7days
- 26 Apr 2024 – 2 May 2024
- Municipalities hit
- 1
- districts
- Started on
- 26 Apr
- 2024
- Heat detections
- 113
- in a single hotspot: 11 MW
- Danger at start
- 39
- Very high · FWI index
- Energy released
- 436MW
- sum of detected power
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 11 days without rain (1 mm or more) when it started. Rain came after the fire: 1.0 mm on 3 May.
This area had burned before
100% of the perimeter overlaps earlier fires recorded since 2016: 873 ha in 2016, 1,747 ha in 2017, 1,169 ha in 2018, 1,507 ha in 2019, 2,390 ha in 2020, 857 ha in 2021, 1,004 ha in 2022, 812 ha in 2023. Part of it burned more than once, so the yearly figures add up to more than the 2,527 ha that had burned before.
- 830 ha Pai fire, February 2020 2,338 ha in total; the hectares shown are those it shares with this fire
- 742 ha Pai fire, February 2017 2,341 ha in total; the hectares shown are those it shares with this fire
- 706 ha Pai fire, February 2019 2,212 ha in total; the hectares shown are those it shares with this fire
- 530 ha Pai fire, March 2020 2,198 ha in total; the hectares shown are those it shares with this fire
- 168 ha Pai fire, March 2018 1,406 ha in total; the hectares shown are those it shares with this fire
- 103 ha Pai fire, March 2017 1,199 ha in total; the hectares shown are those it shares with this fire
- 27 ha Pai fire, April 2020 4,783 ha in total; the hectares shown are those it shares with this fire
What happened to each town
-
Pai where it started2,551 ha reached on 26 Apr1.1 %
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) |
|---|---|---|---|---|---|
| 22 Apr | 41.2 °C | 26 % | 40 km/h | 0.0 mm | Very high 39 |
| 23 Apr | 40.8 °C | 30 % | 38 km/h | 0.1 mm | Very high 39 |
| 24 Apr | 40.0 °C | 32 % | 46 km/h | 0.2 mm | Very high 42 |
| 25 Apr | 38.8 °C | 34 % | 42 km/h | 0.5 mm | Very high 40 |
| 26 Apr | 39.4 °C | 30 % | 46 km/h | 0.2 mm | Very high 41 |
| 27 Apr | 40.2 °C | 30 % | 40 km/h | 0.0 mm | Very high 39 |
| 28 Apr | 41.1 °C | 29 % | 37 km/h | 0.0 mm | Very high 39 |
| 29 Apr | 40.7 °C | 33 % | 44 km/h | 0.0 mm | Very high 41 |
| 30 Apr | 39.9 °C | 32 % | 46 km/h | 0.0 mm | Very high 42 |
| 1 May | 40.4 °C | 30 % | 44 km/h | 0.0 mm | Very high 43 |
| 2 May | 41.2 °C | 28 % | 41 km/h | 0.0 mm | Very high 42 |
| 3 May after | 38.9 °C | 33 % | 43 km/h | 1.0 mm | High 32 |
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 2 May 2024 the air beside the fire reached 35 µg/m³ of PM2.5. That day averaged 28: 1.8 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 · 113Every satellite heat detection, one by one, with time, satellite, power and coordinates.
| Date and time | Satellite | FRP (MW) | Lat | Lon |
|---|
Other fires nearby
- 30,775 haPai24 March 2026 · 24 days · 26 km away
- 22,763 haPai24 March 2026 · 26 days · 33 km away
- 32,440 haMueang Mae Hong Son7 March 2025 · 29 days · 36 km away
- 30,393 haPang Mapha23 March 2026 · 31 days · 37 km away
- 153,263 haPang Mapha19 March 2026 · 37 days · 38 km away
- 18,109 haMueang Mae Hong Son22 March 2026 · 21 days · 38 km away
Frequently asked questions
- How long did the Pai fire last?
- GWIS (Copernicus) dates it between 26 April 2024 and 2 May 2024: 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 2,539 hectares (25.4 km²). It is an estimate: official national figures may differ.
- Which municipalities burned?
- The fire only entered Pai (2,551 ha, 1.1 %).
- What was the weather like?
- During the fire the temperature reached 41.2 °C, humidity dropped to 26 % and gusts hit 46 km/h. The fire danger index (FWI) reached 43, class Very 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
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.