How long did the Li fire last?

GWIS (Copernicus) dates it between 22 March 2026 and 4 April 2026: 14 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 3,891 hectares (38.9 km²). It is an estimate: official national figures may differ.

Which municipalities burned?

The fire entered 2 municipalities: Li (3,252 ha, 1.8 %); Doi Tao (662 ha, 0.8 %).

What was the weather like?

During the fire the temperature reached 36.2 °C, humidity dropped to 25 % and gusts hit 35 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.

TH · Thailand · 2026-03-22 → 2026-04-04

Li fire, 22 March 2026 Li, Doi Tao

Out · last detection 4 Apr 2026, 18:49 UTC

The fire started on 22 March 2026 in Li, Thailand, and satellites saw it burning for 14 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 3,891 hectares from heat detections, spread across 2 municipalities.

It is the 52th largest in Chiang Mai Province since 2016 (of 463 with a page). Number 178 in Thailand in 2026, of 880.

The power measured by the satellite is low (12.1 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: 3,891ha; GWIS perimeter (Copernicus)
Duration: 14days; 22 Mar 2026 – 4 Apr 2026
Municipalities hit: 2; districts
Started on: 22 Mar; 2026
Heat detections: 43; in a single hotspot: 12 MW
Danger at start: 26; High · FWI index
Energy released: 128MW; sum of detected power

Play back 4 Apr 2026

HOTSPOTS BY DAY 22 Mar4 Apr

How it evolved, day by day

222324252627282930311234

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

The weather it burned in

36°high

35km/h · peak gust

25%lowest humidity

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

This area had burned before

57% of the perimeter overlaps earlier fires recorded since 2016: 766 ha in 2017, 678 ha in 2018, 68 ha in 2019, 317 ha in 2021, 2 ha in 2024, 1,675 ha in 2025. Part of it burned more than once, so the yearly figures add up to more than the 2,231 ha that had burned before.

1,096 ha Li fire, March 2025 1,459 ha in total; the hectares shown are those it shares with this fire

What happened to each town

Li where it started

3,252 ha reached on 23 Mar

1.8 %
Doi Tao

662 ha reached on 22 Mar

0.8 %

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)
22 Mar	33.4 °C	35 %	35 km/h	0.0 mm	High 26
23 Mar	33.8 °C	26 %	30 km/h	0.0 mm	High 27
24 Mar	34.3 °C	26 %	26 km/h	0.0 mm	High 28
25 Mar	34.4 °C	27 %	27 km/h	0.0 mm	High 28
26 Mar	35.4 °C	25 %	24 km/h	0.0 mm	High 29
27 Mar	35.4 °C	25 %	32 km/h	0.0 mm	High 31
28 Mar	35.2 °C	30 %	30 km/h	0.0 mm	High 30
29 Mar	35.4 °C	27 %	34 km/h	0.1 mm	High 32
30 Mar	35.6 °C	27 %	27 km/h	0.0 mm	High 31
31 Mar	35.2 °C	31 %	24 km/h	0.0 mm	High 31
1 Apr	35.2 °C	33 %	22 km/h	0.0 mm	High 31
2 Apr	36.0 °C	30 %	28 km/h	0.0 mm	High 30
3 Apr	36.2 °C	29 %	31 km/h	0.0 mm	High 32
4 Apr	34.2 °C	37 %	25 km/h	0.0 mm	High 29
5 Apr after	35.6 °C	35 %	30 km/h	0.0 mm	High 30
6 Apr after	35.2 °C	36 %	25 km/h	0.0 mm	High 30
7 Apr after	35.3 °C	34 %	35 km/h	0.3 mm	High 35
8 Apr after	35.9 °C	27 %	36 km/h	0.0 mm	High 35
9 Apr after	35.1 °C	28 %	34 km/h	0.0 mm	High 34
10 Apr after	35.8 °C	27 %	35 km/h	0.0 mm	High 35
11 Apr after	35.3 °C	28 %	38 km/h	0.0 mm	High 36
12 Apr after	35.9 °C	30 %	28 km/h	0.0 mm	High 33
13 Apr after	36.5 °C	30 %	30 km/h	0.0 mm	High 34
14 Apr after	36.5 °C	29 %	24 km/h	0.0 mm	High 33

Before and after, from space

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

↔

Before · 15 Mar 2026

After · 11 Apr 2026

Before After

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 26 March 2026 the air beside the fire reached 80 µg/m³ of PM2.5. That day averaged 53: 3.5 times the WHO daily guideline (15).

PM2.5 peak80 µg/m³

Days over the guideline18 days

PM1090 µg/m³

Optical depth1.43

WHO 15

2021222324252627282930311234567

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 · 43Every 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 time	Satellite	FRP (MW)	Lat	Lon

Other fires nearby

All fires in Thailand ›

Frequently asked questions

How long did the Li fire last?: GWIS (Copernicus) dates it between 22 March 2026 and 4 April 2026: 14 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 3,891 hectares (38.9 km²). It is an estimate: official national figures may differ.
Which municipalities burned?: The fire entered 2 municipalities: Li (3,252 ha, 1.8 %); Doi Tao (662 ha, 0.8 %).
What was the weather like?: During the fire the temperature reached 36.2 °C, humidity dropped to 25 % and gusts hit 35 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

NASA FIRMS ↗
GWIS · Copernicus ↗

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.

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What really happened?

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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.

Where it burned