Aso fire, April 2021 Aso
The fire started on 11 April 2021 in Aso, Japan, and satellites saw it burning for 1 day. Copernicus’s global GWIS system rebuilt a burnt perimeter of 437 hectares from heat detections, spread across a single municipality.
It is the 34th largest in Kumamoto since 2016 (of 92 with a page). Number 2 in Japan in 2021, of 14.
The power measured by the satellite is low (29.8 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
- 437ha
- GWIS perimeter (Copernicus)
- Duration
- 1day
- 11 Apr 2021 – 11 Apr 2021
- Municipalities hit
- 1
- municipalities
- Started on
- 11 Apr
- 2021
- Heat detections
- 17
- in a single hotspot: 30 MW
- Danger at start
- 9
- Low · FWI index
- Energy released
- 203MW
- sum of detected power
Where it burned
How it evolved, day by day
Fire radiative power detected each day, in megawatts, and number of hotspots. The magenta bar marks the peak day.
The weather it burned in
It had gone 6 days without rain (1 mm or more) when it started. Rain came after the fire: 7.8 mm on 12 Apr.
This area had burned before
65% of the perimeter overlaps earlier fires recorded since 2016: 204 ha in 2016, 281 ha in 2017. Part of it burned more than once, so the yearly figures add up to more than the 286 ha that had burned before.
What happened to each town
-
Aso where it started438 ha1.2 %
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) |
|---|---|---|---|---|---|
| 11 Apr | 17.3 °C | 36 % | 36 km/h | 0.0 mm | Low 9 |
| 12 Apr after | 15.5 °C | 74 % | 52 km/h | 7.8 mm | Very low 0 |
Before and after, from space
Drag the line to compare the same ground before the fire and after it.
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 · 17Every satellite heat detection, one by one, with time, satellite, power and coordinates.
| Date and time | Satellite | FRP (MW) | Lat | Lon |
|---|
Other fires nearby
Frequently asked questions
- How long did the Aso fire last?
- GWIS (Copernicus) dates it between 11 April 2021 and 11 April 2021: 1 day 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 437 hectares (4.4 km²). It is an estimate: official national figures may differ.
- Which municipalities burned?
- The fire only entered Aso (438 ha, 1.2 %).
- What was the weather like?
- During the fire the temperature reached 17.3 °C, humidity dropped to 36 % and gusts hit 36 km/h. The fire danger index (FWI) reached 9, class Low.
- Where does this data come from?
- From the GWIS (Copernicus) burnt perimeter, NASA FIRMS VIIRS hotspots and the administrative boundaries of Japan (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: 119
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
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-ShareAlike 2.0). 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.