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AU · Australia · –

West Arnhem fire, 29 September 2018 West Arnhem

Out · last detection 10 Oct 2018, 05:05 UTC

The fire started on 29 September 2018 in West Arnhem, Australia, and satellites saw it burning for 12 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 10,513 hectares from heat detections, spread across a single municipality.

It is the 1104th largest in Northern Territory since 2016 (of 2853 with a page). Number 359 in Australia in 2018, of 923.

Burnt area
10,513ha
GWIS perimeter (Copernicus)
Duration
12days
29 Sept 2018 – 10 Oct 2018
Municipalities hit
1
local government areas
Started on
29 Sept
2018
Heat detections
365
in a single hotspot: 137 MW
Danger at start
48
Very high · FWI index
Average daily power
304MW
detected power per day, on average

Where it burned

HOTSPOTS BY DAY 29 Sept10 Oct
10 Oct 2018

How it evolved, day by day

29 Sept 2018 · 917 MW · 79 30 Sept 2018 · 783 MW · 81 1 Oct 2018 · 239 MW · 15 2 Oct 2018 · 63 MW · 23 3 Oct 2018 · 305 MW · 47 4 Oct 2018 · 21 MW · 11 5 Oct 2018 · 595 MW · 46 6 Oct 2018 · 43 MW · 5 7 Oct 2018 · 487 MW · 23 8 Oct 2018 · 96 MW · 20 9 Oct 2018 · 30 MW · 7 10 Oct 2018 · 63 MW · 8
29 Sept 2 Oct 5 Oct 8 Oct

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

The weather it burned in

39°high
54km/h · peak gust
14%lowest humidity

It had gone more than two months without rain (1 mm or more) when it started. Rain came after the fire: 5.1 mm on 17 Oct.

This area had burned before

40% of the perimeter overlaps earlier fires recorded since 2016: 2,241 ha in 2016, 2,485 ha in 2017. Part of it burned more than once, so the yearly figures add up to more than the 4,190 ha that had burned before.

How big is it?

10 km
It burned the equivalent of 6.6% of the area of London (105 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. West Arnhem where it started
    10,602 ha reached on 29 Sept
    0.2 %

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 area< 0.1 ha
Residents< 20

Inside the perimeter there was no noticeable built-up land and almost nobody lived there (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)
27 Sept 36.3 °C 19 % 35 km/h 0.0 mm Very high 48
28 Sept 36.2 °C 18 % 38 km/h 0.0 mm Very high 50
29 Sept 35.8 °C 20 % 41 km/h 0.0 mm Extreme 52
30 Sept 36.7 °C 15 % 54 km/h 0.0 mm Extreme 64
1 Oct 35.2 °C 24 % 49 km/h 0.0 mm Extreme 51
2 Oct 33.5 °C 29 % 47 km/h 0.0 mm Very high 48
3 Oct 37.7 °C 18 % 32 km/h 0.0 mm Very high 46
4 Oct 38.0 °C 22 % 38 km/h 0.0 mm Extreme 50
5 Oct 37.2 °C 29 % 32 km/h 0.0 mm Very high 44
6 Oct 38.2 °C 20 % 31 km/h 0.0 mm Very high 46
7 Oct 39.1 °C 14 % 32 km/h 0.0 mm Extreme 51
8 Oct 38.4 °C 21 % 36 km/h 0.0 mm Extreme 55
9 Oct 37.8 °C 24 % 37 km/h 0.0 mm Extreme 51
10 Oct 38.2 °C 19 % 28 km/h 0.0 mm Very high 47
11 Oct after 37.4 °C 26 % 27 km/h 0.0 mm Very high 41
12 Oct after 38.5 °C 26 % 34 km/h 0.0 mm Very high 49
13 Oct after 37.8 °C 27 % 39 km/h 0.0 mm Very high 48
14 Oct after 37.3 °C 34 % 29 km/h 0.0 mm Very high 40
15 Oct after 37.0 °C 33 % 35 km/h 0.3 mm Very high 41
16 Oct after 37.4 °C 33 % 31 km/h 0.0 mm Very high 42
17 Oct after 36.1 °C 32 % 35 km/h 5.1 mm Moderate 14

Its twins: fires that started in the same weather

It started with an FWI of 48.3, a minimum humidity of 20% and more than two months without rain. Fires in the area that started in weather like this since 2016: 31.

FWI at the start 48.3
Minimum humidity 20 %
Days without rain 60+
this fire chosen twins rest of the area
Almost identicalSimilar

Outlines of the closest twins

Unincorporated NT fire, September 2020
8,529 ha 13 days FWI 47.7 Min. humidity 20 % 138 km away, in 2020

First rain (1 mm or more) after it ended: 3.3 mm on 19 Sept.

What happened to them

11 days
median duration
8,171 ha
median area
35 %
went past 10,000 ha
3.9 mm
rain at the end (median; 7 of 31 had it)

It burned an area similar to its twins (10,513 ha against a median of 8,171 ha) and lasted 12 days, against 11 days.

In 24 of 31, 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 3.9 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

5.1 mmfirst rain
17 Oct7 days after it ended
54km/h · max. gust

It was considered over on 10 Oct, and on 17 Oct 5.1 mm fell. We do not know whether the rain or the firefighters put it out. Twins with rain when they ended: 7 of 31, with a median of 3.9 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 · 22 Sept 2018
After · 17 Oct 2018

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 · 365Every 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 Australia

Frequently asked questions

How long did the West Arnhem fire last?
GWIS (Copernicus) dates it between 29 September 2018 and 10 October 2018: 12 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 10,513 hectares (105.1 km²). It is an estimate: official national figures may differ.
Which municipalities burned?
The fire only entered West Arnhem (10,602 ha, 0.2 %).
What was the weather like?
During the fire the temperature reached 39.1 °C, humidity dropped to 14 % and gusts hit 54 km/h. The fire danger index (FWI) reached 64, class Extreme.
Where does this data come from?
From the GWIS (Copernicus) burnt perimeter, NASA FIRMS VIIRS hotspots and the administrative boundaries of Australia (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: 31. Their median duration was 11 days and their median area 8,171 ha; 35 % went past 10,000 ha. In 24 of 31, 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 3.9 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: 000 · 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.

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 000.

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. 365 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 4.0 International (CC BY 4.0)). 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.