AU · Australia · Fire front film

Mapoon fire, 23 July 2026 23 Jul 2026 – 8 Aug 2026

Burned area: 11,480ha
VIIRS hotspots in the film: 288
Passes with fire: 19
Highest FRP of a hotspot: 21MW

Fire front film

How it spread, pass by pass, and what the wind was doing

Each dot is a hotspot the satellite detected as it flew over. The hourly wind flows underneath.

Radiated energy (FRP) of each pass · gusts as the linelocal time · Australia/Brisbane

10 m wind particles Rings by day ash GWIS perimeter (4 Aug) Wind at 850 hPa Wind at 700 hPa

Upper-level wind (850 and 700 hPa) is only available for fires from the last two weeks: the ERA5 archive we use has no pressure levels.

What the film shows

Fastest spread between two passes ≥ 0.58 km/h

7.3 km in 13 h, from the pass on Sat 25 Jul at 01:58 to the one on Sat 25 Jul at 14:32.

Main direction of spread WNW · 289°

Sum of the jumps in the passes with clear spread (6).

Passes in which it spread with the wind 33 %

2 of 6 with the wind, 4 across it and 0 against the surface wind (ERA5).

There is no data between passes. Each VIIRS satellite flies over about twice a day; between one pass and the next the front “jumps” and we do not fill the gap. Clouds and thick smoke also hide hotspots. The wind is the ERA5 reanalysis, with cells of about 25 km: it does not see slope winds or the wind the fire itself whips up.

Satellite passes over the fire, with the spread and the wind between passes
Pass (local time)	Satellite	Hotspots	Total FRP	Spread	Heading	ERA5 wind between passes	Front and wind
Thu 23 Jul · 15:10	Suomi NPP	3	16 MW	start	—	—	—
Fri 24 Jul · 02:16	Suomi NPP	32	52 MW	4.6 km	W 261°	from E at 12 km/h	with the wind (19°)
Sat 25 Jul · 01:58	Suomi NPP	32	29 MW	8.6 km	N 6°	from ESE at 14 km/h	crosswind (80°)
Sat 25 Jul · 14:32	Suomi NPP	47	467 MW	7.3 km	WNW 296°	from ESE at 14 km/h	with the wind (5°)
Sun 26 Jul · 01:37	Suomi NPP	27	22 MW	1.4 km	NE 39°	from ESE at 14 km/h	crosswind (111°)
Sun 26 Jul · 14:14	Suomi NPP	90	451 MW	5.4 km	SSW 192°	from ESE at 10 km/h	crosswind (99°)
Mon 27 Jul · 13:53	Suomi NPP	16	76 MW	0.6 km	no clear spread	—	—
Tue 28 Jul · 13:36	Suomi NPP	3	20 MW	0.4 km	no clear spread	—	—
Thu 30 Jul · 14:38	Suomi NPP	2	16 MW	0.6 km	no clear spread	—	—
Fri 31 Jul · 01:46	Suomi NPP	4	4 MW	0.6 km	no clear spread	—	—
Fri 31 Jul · 14:19	Suomi NPP	9	48 MW	1.2 km	no clear spread	—	—
Sat 1 Aug · 01:26	Suomi NPP	4	4 MW	0.4 km	no clear spread	—	—
Mon 3 Aug · 13:42	NOAA-20	7	61 MW	1.9 km	NE 36°	from ESE at 19 km/h	crosswind (102°)
Tue 4 Aug · 02:30	NOAA-20	3	2 MW	1.3 km	no clear spread	—	—
Wed 5 Aug · 01:52	Suomi NPP	1	1 MW	0.3 km	no clear spread	—	—
Wed 5 Aug · 02:09	NOAA-20	1	1 MW	0.1 km	no clear spread	—	—
Fri 7 Aug · 13:47	Suomi NPP	3	28 MW	1.5 km	no clear spread	—	—
Sat 8 Aug · 02:37	Suomi NPP	1	1 MW	1.3 km	no clear spread	—	—
Sat 8 Aug · 13:30	Suomi NPP	3	30 MW	1.5 km	no clear spread	—	—

How it is calculated (for anyone who wants to check)

Pass: the hotspots from one satellite with less than 20 minutes between them. Spread: the distance from each new hotspot to the nearest earlier hotspot; we take the 90th percentile so a single stray hotspot cannot inflate the figure, and we only count the pass if at least 5 hotspots fall more than 750 m from what had already been seen (those more than 15 km away are another fire and do not count). Speed: the spread divided by the hours since the previous pass, only if 6 hours or more have gone by; it is a minimum, because the front may have moved faster and then stopped. Wind: the vector mean of the hours between the two passes, interpolated between the model grid points around the hotspots that moved. “With the wind” if the heading of the spread and the direction the wind blows towards differ by less than 60°, “crosswind” up to 120° and “against” beyond that.

worldfires methodology

Mapoon fire, 23 July 2026 Wildfires in Australia worldfires methodology