Pai fire, April 2019 Pai
The fire started on 4 April 2019 in Pai, Thailand, and satellites saw it burning for 8 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 1,199 hectares from heat detections, spread across a single municipality.
It is the 502th largest in Mae Hong Son Province since 2016 (of 668 with a page). Number 368 in Thailand in 2019, of 503.
The power measured by the satellite is low (17.4 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
- 1,199ha
- GWIS perimeter (Copernicus)
- Duration
- 8days
- 4 Apr 2019 – 11 Apr 2019
- Municipalities hit
- 1
- districts
- Started on
- 4 Apr
- 2019
- Heat detections
- 36
- in a single hotspot: 17 MW
- Danger at start
- 37
- 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 more than two months without rain (1 mm or more) when it started.
This area had burned before
35% of the perimeter overlaps earlier fires recorded since 2016: 345 ha in 2017, 87 ha in 2018.
What happened to each town
-
Pai where it started1,204 ha reached on 4 Apr0.5 %
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) |
|---|---|---|---|---|---|
| 28 Mar | 32.4 °C | 24 % | 43 km/h | 0.0 mm | High 37 |
| 29 Mar | 34.3 °C | 16 % | 31 km/h | 0.0 mm | Very high 38 |
| 30 Mar | 33.8 °C | 24 % | 31 km/h | 0.0 mm | Very high 41 |
| 31 Mar | 34.1 °C | 21 % | 36 km/h | 0.0 mm | Very high 41 |
| 1 Apr | 34.7 °C | 18 % | 37 km/h | 0.0 mm | Very high 43 |
| 2 Apr | 35.1 °C | 19 % | 36 km/h | 0.0 mm | Very high 42 |
| 3 Apr | 34.3 °C | 24 % | 36 km/h | 0.4 mm | Very high 40 |
| 4 Apr | 34.7 °C | 20 % | 39 km/h | 0.0 mm | Very high 42 |
| 5 Apr | 34.4 °C | 23 % | 36 km/h | 0.0 mm | Very high 42 |
| 6 Apr | 35.1 °C | 22 % | 36 km/h | 0.0 mm | Very high 42 |
| 7 Apr | 35.3 °C | 21 % | 42 km/h | 0.0 mm | Very high 46 |
| 8 Apr | 34.7 °C | 23 % | 44 km/h | 0.0 mm | Very high 44 |
| 9 Apr | 34.9 °C | 23 % | 41 km/h | 0.0 mm | Very high 44 |
| 10 Apr | 35.1 °C | 20 % | 44 km/h | 0.0 mm | Very high 45 |
| 11 Apr | 36.0 °C | 20 % | 41 km/h | 0.0 mm | Very high 45 |
| 12 Apr after | 35.4 °C | 23 % | 38 km/h | 0.0 mm | Very high 44 |
| 13 Apr after | 35.9 °C | 24 % | 35 km/h | 0.0 mm | Very high 44 |
| 14 Apr after | 36.6 °C | 25 % | 39 km/h | 0.0 mm | Very high 44 |
| 15 Apr after | 36.1 °C | 27 % | 40 km/h | 0.0 mm | Very high 43 |
| 16 Apr after | 36.2 °C | 28 % | 32 km/h | 0.0 mm | Very high 39 |
| 17 Apr after | 35.3 °C | 32 % | 47 km/h | 0.0 mm | Very high 40 |
| 18 Apr after | 36.1 °C | 29 % | 47 km/h | 0.1 mm | Very high 41 |
| 19 Apr after | 36.2 °C | 31 % | 46 km/h | 0.2 mm | Very high 41 |
| 20 Apr after | 36.5 °C | 27 % | 40 km/h | 0.0 mm | Very high 41 |
| 21 Apr after | 35.1 °C | 28 % | 40 km/h | 0.0 mm | Very high 39 |
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 · 36Every 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 4 April 2019 and 11 April 2019: 8 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 1,199 hectares (12.0 km²). It is an estimate: official national figures may differ.
- Which municipalities burned?
- The fire only entered Pai (1,204 ha, 0.5 %).
- What was the weather like?
- During the fire the temperature reached 36.0 °C, humidity dropped to 16 % and gusts hit 44 km/h. The fire danger index (FWI) reached 46, 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.