Skip to content
worldfires
TH · Thailand · –

Sop Moei fire, 22 March 2019 สบเมย · Sop Moei, Mae Sariang

Out · last detection 5 Apr 2019, 19:06 UTC

The fire started on 22 March 2019 in Sop Moei, Thailand, and satellites saw it burning for 15 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 4,001 hectares from heat detections, spread across 2 municipalities.

It is the 44th largest in Mae Hong Son Province since 2016 (of 361 with a page). Number 30 in Thailand in 2019, of 385.

The power measured by the satellite is low (17.9 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
4,001ha
GWIS perimeter (Copernicus)
Duration
15days
22 Mar 2019 – 5 Apr 2019
Municipalities hit
2
districts
Started on
22 Mar
2019
Heat detections
169
in a single hotspot: 18 MW
Danger at start
37
High · FWI index
Average daily power
54MW
detected power per day, on average

Where it burned

HOTSPOTS BY DAY 22 Mar5 Apr
5 Apr 2019

How it evolved, day by day

25 Mar 2019 · 4 MW · 5 26 Mar 2019 · 2 MW · 1 28 Mar 2019 · 1 MW · 1 29 Mar 2019 · 8 MW · 4 30 Mar 2019 · 121 MW · 28 31 Mar 2019 · 156 MW · 48 1 Apr 2019 · 125 MW · 34 2 Apr 2019 · 115 MW · 27 3 Apr 2019 · 34 MW · 9 4 Apr 2019 · 12 MW · 4 5 Apr 2019 · 20 MW · 8
25 Mar 31 Mar 4 Apr

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

The weather it burned in

38°high
40km/h · peak gust
23%lowest humidity

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

This area had burned before

48% of the perimeter overlaps earlier fires recorded since 2016: 1,422 ha in 2016, 762 ha in 2017, 496 ha in 2018. Part of it burned more than once, so the yearly figures add up to more than the 1,908 ha that had burned before.

How big is it?

10 km
It burned the equivalent of 2.5% of the area of London (40 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. Sop Moei สบเมย where it started
    4,010 ha reached on 25 Mar
    2.8 %
  2. Mae Sariang แม่สะเรียง
    15 ha
    0.0 %

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 area2.2 ha
Residents≈ 600

Inside the perimeter there were about 2.2 hectares of built-up land and about 600 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)

Started with 60 days without rain: 15 % of the area in Thailand

Day High Min. humidity Peak gust Rain Danger (FWI)
22 Mar 35.6 °C 30 % 31 km/h 0.0 mm High 37
23 Mar 36.9 °C 29 % 31 km/h 0.0 mm High 33
24 Mar 36.6 °C 27 % 38 km/h 0.0 mm Very high 40
25 Mar 37.7 °C 26 % 34 km/h 0.0 mm Very high 38
26 Mar 37.5 °C 28 % 32 km/h 0.0 mm High 36
27 Mar 34.2 °C 46 % 37 km/h 1.5 mm High 37
28 Mar 35.0 °C 34 % 38 km/h 0.0 mm High 25
29 Mar 36.1 °C 25 % 31 km/h 0.0 mm Very high 41
30 Mar 36.3 °C 34 % 31 km/h 0.0 mm High 36
31 Mar 35.7 °C 26 % 38 km/h 0.0 mm Very high 43
1 Apr 36.5 °C 23 % 40 km/h 0.0 mm Very high 49
2 Apr 37.3 °C 27 % 36 km/h 0.0 mm Very high 47
3 Apr 36.9 °C 28 % 32 km/h 0.0 mm Very high 42
4 Apr 36.2 °C 33 % 32 km/h 0.2 mm Very high 38
5 Apr 36.8 °C 30 % 34 km/h 0.1 mm High 37
6 Apr after 36.9 °C 30 % 36 km/h 0.2 mm Very high 41
7 Apr after 36.9 °C 29 % 39 km/h 0.0 mm Very high 45
8 Apr after 36.7 °C 32 % 36 km/h 0.0 mm Very high 43
9 Apr after 36.7 °C 34 % 36 km/h 0.4 mm Very high 43
10 Apr after 37.3 °C 29 % 36 km/h 0.0 mm Very high 40
11 Apr after 38.1 °C 29 % 35 km/h 0.0 mm Very high 40
12 Apr after 37.3 °C 33 % 36 km/h 0.0 mm Very high 39
13 Apr after 37.9 °C 30 % 39 km/h 0.0 mm Very high 41
14 Apr after 37.9 °C 31 % 41 km/h 0.0 mm Very high 43
15 Apr after 38.0 °C 33 % 38 km/h 0.0 mm Very high 43

Its twins: fires that started in the same weather

It started with an FWI of 37.0, a minimum humidity of 30% and more than two months without rain. Fires in the area that started in weather like this since 2016: 23.

FWI at the start 37.0
Minimum humidity 30 %
Days without rain 60+
this fire chosen twins rest of the area
Almost identicalSimilar

Outlines of the closest twins

Mae La Noi fire, March 2020
1,686 ha 12 days FWI 37.6 Min. humidity 30 % 43 km away, in 2020

First rain (1 mm or more) after it ended: none in the following ten days.

What happened to them

12 days
median duration
2,210 ha
median area
100 %
went past 1,000 ha
2.4 mm
rain at the end (median; 11 of 23 had it)

It was 1.8 times larger than the median of its twins and lasted 15 days, against 12 days.

Only 3 of its 23 twins burned more. The weather on the first day does not explain everything: the wind in the following days, the fuel and the firefighting also count. In 12 of 23, not even 1 mm fell in the ten days after the end: they went out without rain. In the rest, the first rainy day brought a median of 2.4 mm.

This is a bank of analogues: it shows what usually happens, not what will happen. With fewer than 15 twins we give no figures. How we calculate it

How it ended

—first rain
—no rain in ten days
40km/h · max. gust

It was considered over on 5 Apr, and not even 1 mm fell in the following ten days: it went out without rain. Twins with rain when they ended: 11 of 23, with a median of 2.4 mm.

Weather on this page: Open-Meteo.com (CC BY 4.0) · Copernicus Climate Change Service (ERA5)

How a twin is chosen

  • Same area: fires that have already ended, less than 250 km from this one, since 2016.
  • Same start: we compare the FWI on the first day, the minimum humidity that day and the run of days without rain before it. The slider sets how much they may differ.
  • Only pages with final weather data (ERA5 reanalysis) calculated in the same way as this fire’s; agricultural and grass burns and pages with data under review are left out.
  • Fires burning at the same time as this one (a week before or after) are left out: they share the same spell of weather and do not count as a precedent.
  • They are sorted by similarity, and the outlines of the first five are drawn.

How we calculate it

Before and after, from space

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

Before · 15 Mar 2019
After · 12 Apr 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 · 169Every 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 Sop Moei fire last?
According to the heat detections seen by satellite inside the perimeter, it burned from 22 March 2019 to 5 April 2019 (15 days). The perimeter dates it from 29 March 2019 to 5 April 2019.
How much area did it burn?
The perimeter GWIS (Copernicus) rebuilt from heat detections is 4,001 hectares (40.0 km²). It is an estimate: official national figures may differ.
Which municipalities burned?
The fire entered 2 municipalities: Sop Moei (4,010 ha, 2.8 %); Mae Sariang (15 ha, 0.0 %).
What was the weather like?
During the fire the temperature reached 37.7 °C, humidity dropped to 23 % and gusts hit 40 km/h. The fire danger index (FWI) reached 49, 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.
How did the fires that started in similar weather in this area end?
Fires less than 250 km away that started since 2016 with a similar FWI, humidity and dry spell: 23. Their median duration was 12 days and their median area 2,210 ha; 100 % went past 1,000 ha. Only 3 of its 23 twins burned more. The weather on the first day does not explain everything: the wind in the following days, the fuel and the firefighting also count. In 12 of 23, not even 1 mm fell in the ten days after the end: they went out without rain. In the rest, the first rainy day brought a median of 2.4 mm.

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 · 1 Changes in area, dates, name, official record or merged pages, compared every night since 24 October 2026.
  1. Start date: 29 March 2019 → 22 March 2019.

RSS Changes to this page With cross-checks and a citable version

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 adjusted with the VIIRS detections inside the perimeter, which said 29 March 2019 to 5 April 2019. 169 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.