Pai fire, 24 March 2026 Pai, Galyani Vadhana
The fire started on 24 March 2026 in Pai, Thailand, and satellites saw it burning for 24 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 30,775 hectares from heat detections, spread across 2 municipalities.
It is the 9th largest in Mae Hong Son Province since 2016 (of 668 with a page). Number 17 in Thailand in 2026, of 880.
The power measured by the satellite is low (26.4 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
- 30,775ha
- GWIS perimeter (Copernicus)
- Duration
- 24days
- 24 Mar 2026 – 16 Apr 2026
- Municipalities hit
- 2
- districts
- Started on
- 24 Mar
- 2026
- Heat detections
- 847
- in a single hotspot: 26 MW
- Danger at start
- 19
- Moderate · FWI index
- Energy released
- 2.4GW
- 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 one day without rain (1 mm or more) when it started. Rain came after the fire: 5.7 mm on 25 Apr.
This area had burned before
91% of the perimeter overlaps earlier fires recorded since 2016: 4,000 ha in 2016, 8,614 ha in 2017, 3,068 ha in 2018, 8,491 ha in 2019, 15,261 ha in 2020, 8,458 ha in 2021, 2,924 ha in 2022, 9,137 ha in 2023, 14,514 ha in 2024, 854 ha in 2025. Part of it burned more than once, so the yearly figures add up to more than the 28,112 ha that had burned before.
- 6,163 ha Pai fire, February 2024 7,308 ha in total; the hectares shown are those it shares with this fire
- 3,927 ha Pai fire, April 2023 4,149 ha in total; the hectares shown are those it shares with this fire
- 2,607 ha Pai fire, February 2020 3,001 ha in total; the hectares shown are those it shares with this fire
- 1,652 ha Pai fire, February 2020 1,655 ha in total; the hectares shown are those it shares with this fire
- 1,644 ha Pai fire, February 2020 1,764 ha in total; the hectares shown are those it shares with this fire
- 1,609 ha Pai fire, February 2017 1,566 ha in total; the hectares shown are those it shares with this fire
- 1,576 ha Pai fire, March 2020 1,724 ha in total; the hectares shown are those it shares with this fire
- 1,380 ha Pai fire, February 2023 1,349 ha in total; the hectares shown are those it shares with this fire
What happened to each town
-
Pai where it started30,902 ha reached on 23 Mar13 %
-
4 ha reached on 2 Apr0.0 %
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) |
|---|---|---|---|---|---|
| 23 Mar | 34.9 °C | 30 % | 39 km/h | 0.0 mm | Moderate 19 |
| 24 Mar | 35.7 °C | 27 % | 31 km/h | 0.0 mm | Moderate 20 |
| 25 Mar | 35.9 °C | 24 % | 36 km/h | 0.0 mm | High 23 |
| 26 Mar | 36.4 °C | 27 % | 35 km/h | 0.0 mm | High 24 |
| 27 Mar | 36.9 °C | 27 % | 38 km/h | 0.0 mm | High 25 |
| 28 Mar | 37.5 °C | 23 % | 41 km/h | 0.0 mm | High 27 |
| 29 Mar | 37.2 °C | 20 % | 49 km/h | 0.0 mm | High 32 |
| 30 Mar | 36.7 °C | 27 % | 43 km/h | 0.0 mm | High 31 |
| 31 Mar | 37.3 °C | 30 % | 37 km/h | 0.0 mm | High 29 |
| 1 Apr | 36.7 °C | 33 % | 29 km/h | 0.0 mm | High 27 |
| 2 Apr | 37.6 °C | 29 % | 36 km/h | 0.0 mm | High 29 |
| 3 Apr | 38.2 °C | 27 % | 36 km/h | 0.0 mm | High 30 |
| 4 Apr | 36.8 °C | 34 % | 33 km/h | 0.0 mm | High 29 |
| 5 Apr | 37.0 °C | 36 % | 36 km/h | 0.0 mm | High 30 |
| 6 Apr | 36.6 °C | 37 % | 29 km/h | 0.1 mm | High 28 |
| 7 Apr | 36.4 °C | 39 % | 39 km/h | 0.3 mm | High 29 |
| 8 Apr | 37.3 °C | 28 % | 38 km/h | 0.0 mm | High 31 |
| 9 Apr | 36.1 °C | 32 % | 44 km/h | 0.2 mm | High 34 |
| 10 Apr | 36.4 °C | 29 % | 49 km/h | 0.0 mm | High 35 |
| 11 Apr | 36.6 °C | 28 % | 48 km/h | 0.0 mm | High 35 |
| 12 Apr | 37.6 °C | 26 % | 36 km/h | 0.0 mm | High 33 |
| 13 Apr | 38.1 °C | 28 % | 36 km/h | 0.0 mm | High 33 |
| 14 Apr | 38.0 °C | 31 % | 30 km/h | 0.0 mm | High 32 |
| 15 Apr | 38.5 °C | 28 % | 37 km/h | 0.0 mm | High 35 |
| 16 Apr | 37.0 °C | 31 % | 30 km/h | 0.0 mm | High 33 |
| 17 Apr after | 37.1 °C | 32 % | 22 km/h | 0.0 mm | High 32 |
| 18 Apr after | 36.6 °C | 36 % | 30 km/h | 0.0 mm | High 32 |
| 19 Apr after | 37.4 °C | 32 % | 42 km/h | 0.4 mm | High 37 |
| 20 Apr after | 36.6 °C | 35 % | 35 km/h | 0.0 mm | High 34 |
| 21 Apr after | 38.0 °C | 35 % | 35 km/h | 0.3 mm | High 35 |
| 22 Apr after | 39.0 °C | 30 % | 35 km/h | 0.2 mm | High 34 |
| 23 Apr after | 36.9 °C | 39 % | 28 km/h | 0.1 mm | High 30 |
| 24 Apr after | 38.3 °C | 32 % | 24 km/h | 0.0 mm | High 30 |
| 25 Apr after | 33.7 °C | 51 % | 36 km/h | 5.7 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.
The smoke
CAMS · CopernicusOn 17 April 2026 the air beside the fire reached 128 µg/m³ of PM2.5. That day averaged 68: 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 · 847Every satellite heat detection, one by one, with time, satellite, power and coordinates.
| Date and time | Satellite | FRP (MW) | Lat | Lon |
|---|
Other fires nearby
Frequently asked questions
- How long did the Pai fire last?
- GWIS (Copernicus) dates it between 24 March 2026 and 16 April 2026: 24 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 30,775 hectares (307.8 km²). It is an estimate: official national figures may differ.
- Which municipalities burned?
- The fire entered 2 municipalities: Pai (30,902 ha, 13 %); Galyani Vadhana (4 ha, 0.0 %).
- What was the weather like?
- During the fire the temperature reached 38.5 °C, humidity dropped to 20 % and gusts hit 49 km/h. The fire danger index (FWI) reached 35, 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
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.