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Calai fire, 1 September 2021 Calai

Out · last detection 21 Sept 2021, 11:57 UTC

The fire started on 1 September 2021 in Calai, Angola, and satellites saw it burning for 21 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 10,800 hectares from heat detections, spread across a single municipality.

It is the 168th largest in Cuando Cubango since 2016 (of 660 with a page). Number 28 in Angola in 2021, of 126.

Compare with…

Suggestions: Calai · 2019Calai · 2017Calai · 2026Calai · 2024

Burnt area
10,800ha
GWIS perimeter (Copernicus)
Duration
21days
1 Sept 2021 – 21 Sept 2021
Municipalities hit
1
municipalities
Started on
1 Sept
2021
Heat detections
466
in a single hotspot: 95 MW
Danger at start
51
Extreme · FWI index
Average daily power
212MW
detected power per day, on average

Where it burned

HOTSPOTS BY DAY 1 Sept21 Sept
21 Sept 2021

How it evolved, day by day

2 Sept 2021 · 8 MW · 2 3 Sept 2021 · 80 MW · 6 4 Sept 2021 · 11 MW · 1 5 Sept 2021 · 56 MW · 5 6 Sept 2021 · 16 MW · 2 7 Sept 2021 · 39 MW · 9 8 Sept 2021 · 28 MW · 5 9 Sept 2021 · 142 MW · 25 10 Sept 2021 · 82 MW · 13 11 Sept 2021 · 105 MW · 14 12 Sept 2021 · 119 MW · 17 13 Sept 2021 · 252 MW · 14 14 Sept 2021 · 465 MW · 38 15 Sept 2021 · 288 MW · 26 16 Sept 2021 · 1,074 MW · 75 17 Sept 2021 · 568 MW · 82 18 Sept 2021 · 281 MW · 63 19 Sept 2021 · 328 MW · 44 20 Sept 2021 · 301 MW · 24 21 Sept 2021 · 5 MW · 1
2 Sept 5 Sept 8 Sept 11 Sept 14 Sept 16 Sept 17 Sept 20 Sept

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
55km/h · peak gust
10%lowest humidity

It had gone more than two months without rain (1 mm or more) when it started.

This area had burned before

33% of the perimeter overlaps earlier fires recorded since 2016: 532 ha in 2017, 1,805 ha in 2018, 1,868 ha in 2019. Part of it burned more than once, so the yearly figures add up to more than the 3,611 ha that had burned before.

How big is it?

10 km
It burned the equivalent of 6.8% of the area of London (108 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. Calai where it started
    10,847 ha reached on 2 Sept
    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 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)
1 Sept 32.7 °C 13 % 39 km/h 0.0 mm Extreme 51
2 Sept 32.9 °C 12 % 41 km/h 0.0 mm Extreme 53
3 Sept 31.8 °C 14 % 39 km/h 0.0 mm Extreme 52
4 Sept 33.3 °C 13 % 32 km/h 0.0 mm Very high 49
5 Sept 34.2 °C 14 % 35 km/h 0.0 mm Extreme 50
6 Sept 34.7 °C 15 % 36 km/h 0.0 mm Extreme 50
7 Sept 34.0 °C 14 % 25 km/h 0.0 mm Very high 48
8 Sept 34.9 °C 14 % 38 km/h 0.0 mm Extreme 53
9 Sept 33.1 °C 18 % 42 km/h 0.0 mm Extreme 55
10 Sept 31.9 °C 18 % 55 km/h 0.0 mm Extreme 65
11 Sept 30.2 °C 19 % 48 km/h 0.0 mm Extreme 58
12 Sept 29.7 °C 21 % 44 km/h 0.0 mm Extreme 51
13 Sept 31.5 °C 15 % 29 km/h 0.0 mm Very high 43
14 Sept 33.7 °C 10 % 29 km/h 0.0 mm Very high 47
15 Sept 35.0 °C 11 % 29 km/h 0.0 mm Very high 47
16 Sept 35.4 °C 12 % 35 km/h 0.0 mm Extreme 52
17 Sept 34.0 °C 11 % 40 km/h 0.0 mm Extreme 57
18 Sept 35.0 °C 12 % 38 km/h 0.0 mm Extreme 55
19 Sept 33.2 °C 20 % 42 km/h 0.0 mm Extreme 56
20 Sept 33.6 °C 20 % 27 km/h 0.0 mm Very high 46
21 Sept 35.5 °C 14 % 32 km/h 0.0 mm Very high 47
22 Sept after 35.8 °C 13 % 41 km/h 0.0 mm Extreme 56
23 Sept after 35.0 °C 13 % 42 km/h 0.0 mm Extreme 57
24 Sept after 34.6 °C 13 % 40 km/h 0.0 mm Extreme 55
25 Sept after 34.1 °C 12 % 45 km/h 0.0 mm Extreme 60
26 Sept after 34.1 °C 10 % 40 km/h 0.0 mm Extreme 56
27 Sept after 35.2 °C 10 % 39 km/h 0.0 mm Extreme 57
28 Sept after 35.1 °C 12 % 41 km/h 0.0 mm Extreme 60
29 Sept after 35.6 °C 13 % 26 km/h 0.0 mm Very high 50
30 Sept after 35.6 °C 14 % 28 km/h 0.0 mm Extreme 50
1 Oct after 33.3 °C 11 % 37 km/h 0.0 mm Extreme 56

Before and after, from space

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

Before · 25 Aug 2021
After · 28 Sept 2021

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 · 466Every 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 Angola ›

Frequently asked questions

How long did the Calai fire last?
According to the heat detections seen by satellite inside the perimeter, it burned from 1 September 2021 to 21 September 2021 (21 days). The perimeter dates it from 7 September 2021 to 20 September 2021.
How much area did it burn?
The perimeter GWIS (Copernicus) rebuilt from heat detections is 10,800 hectares (108.0 km²). It is an estimate: official national figures may differ.
Which municipalities burned?
The fire only entered Calai (10,847 ha, 1.4 %).
What was the weather like?
During the fire the temperature reached 35.5 °C, humidity dropped to 10 % and gusts hit 55 km/h. The fire danger index (FWI) reached 65, class Extreme.
Where does this data come from?
From the GWIS (Copernicus) burnt perimeter, NASA FIRMS VIIRS hotspots and the administrative boundaries of Angola (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.

Satellite cross-check

History of this page · 2 Changes in area, dates, name, official record or merged pages, compared every night since 24 October 2026.
  1. Last day with fire: 20 September 2021 → 21 September 2021.
  2. Start date: 7 September 2021 → 1 September 2021.

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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How we know this
  • Perimeter: GWIS (Copernicus), rebuilt from heat detections rather than mapped on imagery.
  • Dates adjusted with the VIIRS detections inside the perimeter, which said 7 September 2021 to 20 September 2021. 466 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 (Public Domain). 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.