Pai fire, 3 March 2021 Pai
The fire started on 3 March 2021 in Pai, Thailand, and satellites saw it burning for 5 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 1,174 hectares from heat detections, spread across a single municipality.
It is the 519th largest in Mae Hong Son Province since 2016 (of 668 with a page). Number 198 in Thailand in 2021, of 268.
The power measured by the satellite is low (15.8 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
- 1,174ha
- GWIS perimeter (Copernicus)
- Duration
- 5days
- 3 Mar 2021 – 7 Mar 2021
- Municipalities hit
- 1
- districts
- Started on
- 3 Mar
- 2021
- Heat detections
- 37
- in a single hotspot: 16 MW
- Danger at start
- 26
- High · FWI index
- Energy released
- 116MW
- 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 12 days without rain (1 mm or more) when it started.
This area had burned before
78% of the perimeter overlaps earlier fires recorded since 2016: 516 ha in 2017, 295 ha in 2018, 775 ha in 2019, 34 ha in 2020. Part of it burned more than once, so the yearly figures add up to more than the 918 ha that had burned before.
What happened to each town
-
Pai where it started1,179 ha reached on 3 Mar0.5 %
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) |
|---|---|---|---|---|---|
| 3 Mar | 32.4 °C | 28 % | 43 km/h | 0.0 mm | High 26 |
| 4 Mar | 33.1 °C | 26 % | 47 km/h | 0.0 mm | High 28 |
| 5 Mar | 33.2 °C | 17 % | 48 km/h | 0.0 mm | High 31 |
| 6 Mar | 33.0 °C | 15 % | 40 km/h | 0.0 mm | High 31 |
| 7 Mar | 33.6 °C | 17 % | 32 km/h | 0.0 mm | High 30 |
| 8 Mar after | 33.3 °C | 20 % | 34 km/h | 0.0 mm | High 31 |
| 9 Mar after | 33.7 °C | 20 % | 25 km/h | 0.0 mm | High 29 |
| 10 Mar after | 33.4 °C | 26 % | 28 km/h | 0.0 mm | High 27 |
| 11 Mar after | 33.5 °C | 27 % | 20 km/h | 0.0 mm | High 28 |
| 12 Mar after | 34.0 °C | 26 % | 23 km/h | 0.0 mm | High 27 |
| 13 Mar after | 35.0 °C | 21 % | 20 km/h | 0.0 mm | High 29 |
| 14 Mar after | 33.3 °C | 32 % | 32 km/h | 0.0 mm | High 28 |
| 15 Mar after | 35.1 °C | 25 % | 34 km/h | 0.0 mm | High 30 |
| 16 Mar after | 35.8 °C | 22 % | 28 km/h | 0.0 mm | High 29 |
| 17 Mar after | 36.7 °C | 23 % | 28 km/h | 0.0 mm | High 30 |
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.
Detections table · 37Every 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 3 March 2021 and 7 March 2021: 5 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 1,174 hectares (11.7 km²). It is an estimate: official national figures may differ.
- Which municipalities burned?
- The fire only entered Pai (1,179 ha, 0.5 %).
- What was the weather like?
- During the fire the temperature reached 33.6 °C, humidity dropped to 15 % and gusts hit 48 km/h. The fire danger index (FWI) reached 31, 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.