How long did the Pak Phli fire last?

GWIS (Copernicus) dates it between 24 January 2023 and 1 February 2023: 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 1,226 hectares (12.3 km²). It is an estimate: official national figures may differ.

Which municipalities burned?

The fire entered 2 municipalities: Mueang Nakhon Nayok (627 ha, 0.8 %); Pak Phli (605 ha, 1.4 %).

What was the weather like?

During the fire the temperature reached 34.6 °C, humidity dropped to 32 % and gusts hit 52 km/h. The fire danger index (FWI) reached 27, 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 · 2023-01-24 → 2023-02-01

Pak Phli fire, January 2023 ปากพลี · Mueang Nakhon Nayok, Pak Phli

Out · last detection 1 Feb 2023, 06:24 UTC

The fire started on 24 January 2023 in Pak Phli, Thailand, and satellites saw it burning for 9 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 1,226 hectares from heat detections, spread across 2 municipalities.

It is the 5th largest in Nakhon Nayok Province since 2016 (of 10 with a page). Number 262 in Thailand in 2023, of 369.

The power measured by the satellite is low (18.0 MW in the strongest hotspot), more typical of grass or stubble burning, or a slow surface fire, than of a large crown fire.

Compare with…

Suggestions: Pak Phli · 2026 Pak Phli · 2026 Pak Phli · 2026 Mueang Prachin Buri · 2025

Burnt area: 1,226ha; GWIS perimeter (Copernicus)
Duration: 9days; 24 Jan 2023 – 1 Feb 2023
Municipalities hit: 2; districts
Started on: 24 Jan; 2023
Heat detections: 28; in a single hotspot: 18 MW
Danger at start: 20; Moderate · FWI index
Average daily power: 17MW; detected power per day, on average

HOTSPOTS BY DAY 24 Jan1 Feb

Play back 1 Feb 2023

How it evolved, day by day

24 Jan 25 Jan 26 Jan 28 Jan 30 Jan

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

The weather it burned in

35°high

52km/h · peak gust

32%lowest humidity

It had gone 6 days without rain (1 mm or more) when it started. Rain came after the fire: 1.5 mm on 3 Feb.

This area had burned before

83% of the perimeter overlaps earlier fires recorded since 2016: 300 ha in 2016, 424 ha in 2017, 456 ha in 2018, 353 ha in 2019, 891 ha in 2020, 503 ha in 2021, 667 ha in 2022. Part of it burned more than once, so the yearly figures add up to more than the 1,013 ha that had burned before.

How big is it?

It burned the equivalent of 0.8% of the area of London (12 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

Mueang Nakhon Nayok เมืองนครนายก

627 ha

0.8 %
Pak Phli ปากพลี where it started

605 ha

1.4 %

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 2025

Built-up area12 ha

Residents≈ 650

Inside the perimeter there were about 12 hectares of built-up land and about 650 residents (GHSL 2025, 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. The GHSL 2025 epoch is a projection made from 2020 and earlier data.

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)
18 Jan	31.7 °C	46 %	41 km/h	0.0 mm	Moderate 20
19 Jan	31.5 °C	40 %	31 km/h	0.0 mm	Moderate 18
20 Jan	31.8 °C	42 %	31 km/h	0.0 mm	Moderate 18
21 Jan	32.6 °C	35 %	21 km/h	0.0 mm	Moderate 18
22 Jan	33.6 °C	32 %	19 km/h	0.0 mm	Moderate 19
23 Jan	34.6 °C	35 %	16 km/h	0.0 mm	Moderate 19
24 Jan	33.1 °C	44 %	52 km/h	0.0 mm	High 27
25 Jan	29.5 °C	41 %	41 km/h	0.0 mm	High 26
26 Jan	31.8 °C	40 %	18 km/h	0.0 mm	Moderate 19
27 Jan	32.0 °C	38 %	34 km/h	0.0 mm	High 23
28 Jan	29.5 °C	43 %	42 km/h	0.0 mm	High 25
29 Jan	28.2 °C	37 %	44 km/h	0.0 mm	High 27
30 Jan	28.7 °C	35 %	32 km/h	0.0 mm	High 22
31 Jan	31.2 °C	35 %	17 km/h	0.0 mm	Moderate 20
1 Feb	33.5 °C	36 %	19 km/h	0.0 mm	Moderate 21
2 Feb after	35.1 °C	41 %	20 km/h	0.0 mm	Moderate 21
3 Feb after	33.0 °C	53 %	25 km/h	1.5 mm	Low 8

Before and after, from space

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

↔

Before · 17 Jan 2023

After · 8 Feb 2023

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 1 February 2023 the air beside the fire reached 240 µg/m³ of PM2.5. That day averaged 110: 7.4 times the WHO daily guideline (15).

PM2.5 peak240 µg/m³

Days over the guideline11 days

PM10344 µg/m³

Optical depth1.01

WHO 15

222324252627282930311234

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 · 28Every 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 Pak Phli fire last?: GWIS (Copernicus) dates it between 24 January 2023 and 1 February 2023: 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 1,226 hectares (12.3 km²). It is an estimate: official national figures may differ.
Which municipalities burned?: The fire entered 2 municipalities: Mueang Nakhon Nayok (627 ha, 0.8 %); Pak Phli (605 ha, 1.4 %).
What was the weather like?: During the fire the temperature reached 34.6 °C, humidity dropped to 32 % and gusts hit 52 km/h. The fire danger index (FWI) reached 27, 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 · Emergency number and official warnings ›

Satellite cross-check

NASA FIRMS ↗
GWIS · Copernicus ↗

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.

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What do you think is wrong?

Dates or duration Place or towns Burned area Name It was not a wildfire Same fire as another page Something else

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.

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. 28 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 2025, 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.

Where it burned