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Pai fire, 15 March 2019 ปาย · Pai

Out · last detection 22 Mar 2019, 18:28 UTC

The fire started on 15 March 2019 in Pai, Thailand, and satellites saw it burning for 9 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 2,326 hectares from heat detections, spread across a single municipality.

It is the 124th largest in Mae Hong Son Province since 2016 (of 387 with a page). Number 84 in Thailand in 2019, of 385.

Compare with…

Suggestions: Pai · 2017Pai · 2026Pang Mapha · 2024Pai · 2026

Burnt area
2,326ha
GWIS perimeter (Copernicus)
Duration
9days
15 Mar 2019 – 23 Mar 2019
Municipalities hit
1
districts
Started on
15 Mar
2019
Heat detections
86
in a single hotspot: 44 MW
Danger at start
36
High · FWI index
Average daily power
34MW
detected power per day, on average

Where it burned

HOTSPOTS BY DAY 15 Mar23 Mar
22 Mar 2019

How it evolved, day by day

15 Mar 2019 · 8 MW · 3 16 Mar 2019 · 7 MW · 4 17 Mar 2019 · 13 MW · 10 18 Mar 2019 · 18 MW · 7 19 Mar 2019 · 81 MW · 16 20 Mar 2019 · 102 MW · 26 21 Mar 2019 · 39 MW · 9 22 Mar 2019 · 6 MW · 4
15 Mar 17 Mar 19 Mar 20 Mar 21 Mar

Fire radiative power detected each day, in megawatts, and number of hotspots. The magenta bar marks the peak day.

The weather it burned in

37°high
54km/h · peak gust
18%lowest humidity

It had gone more than two months without rain (1 mm or more) when it started.

This area had burned before

78% of the perimeter overlaps earlier fires recorded since 2016: 656 ha in 2016, 1,461 ha in 2017, 270 ha in 2018. Part of it burned more than once, so the yearly figures add up to more than the 1,824 ha that had burned before.

How big is it?

10 km
It burned the equivalent of 1.5% of the area of London (23 km² against 1,583 km²).

London boundary: geoBoundaries · Office for National Statistics (Open Government Licence v3.0).

This compares size, not location: both shapes are at the same scale, north up, centred on each other.

What happened to each town

  1. Pai ปาย where it started
    2,339 ha
    1.0 %

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 2020
Built-up area1.3 ha
Residents≈ 100

Inside the perimeter there were about 1.3 hectares of built-up land and about 100 residents (GHSL 2020, 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.

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)
14 Mar 35.8 °C 20 % 23 km/h 0.0 mm High 36
15 Mar 35.7 °C 24 % 27 km/h 0.0 mm High 36
16 Mar 35.2 °C 27 % 34 km/h 0.0 mm Very high 38
17 Mar 36.4 °C 18 % 36 km/h 0.0 mm Very high 41
18 Mar 36.6 °C 19 % 42 km/h 0.0 mm Very high 43
19 Mar 34.7 °C 25 % 54 km/h 0.0 mm Very high 46
20 Mar 34.9 °C 23 % 50 km/h 0.0 mm Very high 45
21 Mar 35.5 °C 21 % 40 km/h 0.0 mm Very high 42
22 Mar 35.6 °C 21 % 31 km/h 0.0 mm Very high 39
23 Mar 36.5 °C 20 % 24 km/h 0.0 mm High 38
24 Mar after 37.0 °C 19 % 36 km/h 0.0 mm Very high 42
25 Mar after 37.5 °C 22 % 29 km/h 0.0 mm Very high 40
26 Mar after 37.1 °C 20 % 30 km/h 0.0 mm Very high 40
27 Mar after 35.6 °C 28 % 45 km/h 0.0 mm Very high 43
28 Mar after 34.8 °C 25 % 47 km/h 0.0 mm Very high 45
29 Mar after 37.0 °C 15 % 32 km/h 0.0 mm Very high 43
30 Mar after 36.3 °C 23 % 30 km/h 0.0 mm Very high 42
31 Mar after 36.7 °C 22 % 35 km/h 0.0 mm Very high 43
1 Apr after 37.2 °C 18 % 34 km/h 0.0 mm Very high 44
2 Apr after 37.3 °C 19 % 35 km/h 0.0 mm Very high 44

Before and after, from space

Drag the line to compare the same ground before the fire and after it.

Before · 8 Mar 2019
After · 30 Mar 2019

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 · 86Every satellite heat detection, one by one, with time, satellite, power and coordinates.
⬇ Download CSV Times in UTC. Each detection is a 375 m pixel: a large fire yields hundreds per pass.
Date and timeSatelliteFRP (MW)LatLon

Other fires nearby

All fires in Thailand ›

Frequently asked questions

How long did the Pai fire last?
GWIS (Copernicus) dates it between 15 March 2019 and 23 March 2019: 9 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 2,326 hectares (23.3 km²). It is an estimate: official national figures may differ.
Which municipalities burned?
The fire only entered Pai (2,339 ha, 1.0 %).
What was the weather like?
During the fire the temperature reached 36.6 °C, humidity dropped to 18 % and gusts hit 54 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 · Emergency number and official warnings ›

Satellite cross-check

History of this page Changes in area, dates, name, official record or merged pages, compared every night since 24 October 2026.

No changes since 24 October 2026.

RSS Changes to this page

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
What do you think is wrong?

We will only use your email to reply about this report. Privacy. This is not an emergency service: if there is a fire now, call 199 · 191.

How we know this
  • Perimeter: GWIS (Copernicus), rebuilt from heat detections rather than mapped on imagery.
  • Dates from the perimeter: the VIIRS detections inside it did not change them. 86 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 2020, 100 m cells), summed inside the perimeter: an estimate of what was there, not a damage count.

How we build fire pages: methodology ›

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.