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Long fire, April 2023 Long, Mae Tha

Out · last detection 7 Apr 2023, 18:38 UTC

The fire started on 3 April 2023 in Long, Thailand, and satellites saw it burning for 5 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 2,730 hectares from heat detections, spread across 2 municipalities.

It is the 22th largest in Phrae Province since 2016 (of 120 with a page). Number 93 in Thailand in 2023, of 500.

The power measured by the satellite is low (7.0 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
2,730ha
GWIS perimeter (Copernicus)
Duration
5days
3 Apr 2023 – 7 Apr 2023
Municipalities hit
2
districts
Started on
3 Apr
2023
Heat detections
79
in a single hotspot: 7 MW
Danger at start
29
High · FWI index
Energy released
193MW
sum of detected power

Where it burned

7 Apr 2023
HOTSPOTS BY DAY 3 Apr7 Apr

How it evolved, day by day

34567

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
33km/h · peak gust
26%lowest humidity

It had gone 8 days without rain (1 mm or more) when it started.

This area had burned before

76% of the perimeter overlaps earlier fires recorded since 2016: 1,646 ha in 2016, 121 ha in 2017, 733 ha in 2019, 1,551 ha in 2020. Part of it burned more than once, so the yearly figures add up to more than the 2,088 ha that had burned before.

What happened to each town

  1. Long where it started
    2,464 ha reached on 3 Apr
    1.9 %
  2. Mae Tha
    280 ha reached on 4 Apr
    0.4 %

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)
30 Mar 35.9 °C 32 % 26 km/h 0.0 mm High 29
31 Mar 36.2 °C 32 % 22 km/h 0.0 mm High 29
1 Apr 35.5 °C 36 % 28 km/h 0.0 mm High 29
2 Apr 36.4 °C 29 % 33 km/h 0.0 mm High 32
3 Apr 36.3 °C 26 % 32 km/h 0.0 mm High 32
4 Apr 36.6 °C 28 % 28 km/h 0.0 mm High 31
5 Apr 36.5 °C 27 % 19 km/h 0.0 mm High 30
6 Apr 36.9 °C 31 % 20 km/h 0.0 mm High 32
7 Apr 37.0 °C 33 % 23 km/h 0.0 mm High 32
8 Apr after 36.7 °C 37 % 25 km/h 0.0 mm High 31
9 Apr after 35.7 °C 37 % 35 km/h 0.0 mm High 33
10 Apr after 37.5 °C 32 % 23 km/h 0.0 mm High 30
11 Apr after 38.2 °C 33 % 23 km/h 0.0 mm High 31
12 Apr after 38.3 °C 32 % 22 km/h 0.0 mm High 31
13 Apr after 37.9 °C 36 % 20 km/h 0.0 mm High 32
14 Apr after 38.6 °C 32 % 19 km/h 0.0 mm High 32
15 Apr after 38.6 °C 33 % 22 km/h 0.0 mm High 32
16 Apr after 36.9 °C 34 % 31 km/h 0.0 mm High 35
17 Apr after 37.7 °C 33 % 28 km/h 0.0 mm High 34

Before and after, from space

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

Before · 27 Mar 2023
After · 14 Apr 2023

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 · Copernicus

On 6 April 2023 the air beside the fire reached 90 µg/m³ of PM2.5. That day averaged 57: 3.8 times the WHO daily guideline (15).

PM2.5 peak90 µg/m³
Days over the guideline10 days
PM10129 µg/m³
Optical depth1.43
12345678910
Good Fair Moderate Poor Very poor Extremely poor

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 · 79Every 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 Long fire last?
GWIS (Copernicus) dates it between 3 April 2023 and 7 April 2023: 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 2,730 hectares (27.3 km²). It is an estimate: official national figures may differ.
Which municipalities burned?
The fire entered 2 municipalities: Long (2,464 ha, 1.9 %); Mae Tha (280 ha, 0.4 %).
What was the weather like?
During the fire the temperature reached 37.0 °C, humidity dropped to 26 % and gusts hit 33 km/h. The fire danger index (FWI) reached 32, 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
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.

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.