Burned area
satellite only1,276ha
Perimeter published by GWIS (Copernicus).
- Source
- GWIS (Copernicus)
- Date
- 17 Mar 2023 – 27 Mar 2023
+− cross-check
No official record is matched to this page to compare it with.
SL · Sierra Leone · –
Nieni fire, 17 March 2023 Nieni, Sandor
Out · last detection 27 Mar 2023, 14:37 UTC
The fire started on 17 March 2023 in Nieni, Sierra Leone, and satellites saw it burning for 11 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 1,276 hectares from heat detections, spread across 2 municipalities.
It is the 520th largest in Northern since 2016 (of 937 with a page). Number 84 in Sierra Leone in 2023, of 160.
Use this data
Compare with…
Suggestions: Kunike · 2020Kunike · 2020Nieni · 2021Nieni · 2019
Use this data
Fire page data · version 2026-10-27matches the official recordwith caveatssatellite onlymodel
When copying, the sentence is
Tick the figures you want: they make up the lede and the CSV.
Duration by satellite
satellite only11days
17 Mar 2023 to 27 Mar 2023: first and last day with fire on the page.
- Source
- GWIS (Copernicus) · NASA FIRMS · VIIRS
- Date
- last detection: 27 Mar 2023, 14:37 UTC
+− cross-check
Satellites pass a few times a day and cloud or smoke can hide the fire: a lack of detections is not an official extinction. Each country’s emergency service declares a fire contained or out.
Start
satellite only17 Mar 2023
First day with fire seen by the satellites or the perimeter.
- Source
- GWIS (Copernicus) · NASA FIRMS · VIIRS
- Date
- 17 Mar 2023
+− cross-check
No official record is matched to this page, so the alert time and the cause are not known here.
Hotspots
satellite only40
VIIRS detections at 375 m. Most intense hotspot: 141 MW.
- Source
- NASA FIRMS · VIIRS (Suomi NPP)
- Date
- 17 Mar 2023 – 27 Mar 2023
+− cross-check
There is no official record to compare with. Each hotspot is a pixel detected in one satellite pass, not a separate fire.
The worst day
satellite only242MW
Total radiative power on 25 March 2023; hotspots that day: 6.
- Source
- NASA FIRMS · VIIRS (FRP)
- Date
- 25 Mar 2023
+− cross-check
Fire radiative power (FRP) measures the energy the fire gives off when the satellite passes. Added up by day, it compares intensity, not area.
Danger at the start
model25.9FWI · high
Fire Weather Index (Canadian system) computed by WorldFires for the day the fire started. Consecutive days without rain before: 0.
- Source
- WorldFires calculation (Canadian FWI system)
- Date
- 17 Mar 2023, local noon
- Model
- ERA5 0,25° (ECMWF · Copernicus C3S) · Open-Meteo.com
+− cross-check
This is an index computed from weather model data, not a measurement of the fire nor an official warning. Danger warnings are issued by each country’s authority. Emergency number and official warnings
Weather during the fire
model36.2°C · 39% RH
High of 36.2 °C and minimum humidity of 39% on 25 March 2023; gusts of 32 km/h on 22 March 2023.
- Source
- weather model at the fire’s grid cell
- Date
- 17 Mar 2023 – 27 Mar 2023
- Model
- ERA5 0,25° (ECMWF · Copernicus C3S) · Open-Meteo.com
+− cross-check
These are model values for a cell of about 25 km, not from a weather station: they may differ from what was measured on the ground.
Living inside
model≈ 350people
Estimated residents inside the perimeter and 0.98 ha of built-up area (100 m grid, epoch 2025).
- Source
- GHSL R2023A · JRC
- Date
- calculated on 24 October 2026
+− cross-check
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.
This page’s change log has been kept since 24 October 2026: every night what it publishes is compared and the difference is logged. Anything earlier is reconstructed from each source’s date and marked as reconstructed.
Show
-
· reconstructed weatherWeather and FWI computed from the ERA5 reanalysis
-
logLast day with fire: 26 March 2023 → 27 March 2023.
-
logStart date: 24 March 2023 → 17 March 2023.
-
· reconstructed GHSLPopulation and built-up area computed
What was saved on 27 October 2026
Every night a snapshot of what the page shows is saved. If anything changes, it appears in the list as a log entry.
- Area
- 1,276 ha
- Dates
- 17 Mar 2023 – 27 Mar 2023
- Name
- Nieni
- Official record
- —
Versioned permanent link
https://worldfires.org/en/fire/nieni-2023-03-10?v=2026-10-27A version keeps the area, dates, name and official record; the area as it was logged (changes under 2% are not logged). The map, hotspots and weather always show today’s data.
Citation
A lede of about 60 words figures only, no adjectives
CSV for this fire nieni-2023-03-10.csv · daily, no individual hotspots
| fecha | focos_viirs | frp_mw | tmax_c | tmin_c | hr_min_pct | viento_max_kmh | racha_max_kmh | precip_mm | fwi | clase_fwi | dentro_del_incendio |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 2023-03-17 | 1 | 4 | 35.3 | 22.4 | 33 | 11.5 | 31 | 0 | 25.9 | alto | 1 |
| 2023-03-18 | 5 | 229 | 34.6 | 21.1 | 32 | 14.8 | 29.9 | 0 | 29.8 | alto | 1 |
| 2023-03-19 | 2 | 8 | 34.5 | 20.7 | 34 | 14.9 | 29.2 | 0.1 | 30.4 | alto | 1 |
| 2023-03-20 | 0 | 0 | 35.2 | 21.2 | 29 | 14.6 | 29.9 | 0 | 32.3 | alto | 1 |
| 2023-03-21 | 0 | 0 | 34.5 | 21 | 40 | 14.1 | 30.2 | 0 | 30.9 | alto | 1 |
| 2023-03-22 | 0 | 0 | 33.6 | 23.1 | 43 | 15.7 | 32.4 | 1.1 | 22 | alto | 1 |
| 2023-03-23 | 1 | 4 | 33.6 | 23.1 | 50 | 13.1 | 30.6 | 2.8 | 8.9 | bajo | 1 |
| 2023-03-24 | 10 | 120 | 34.3 | 23 | 36 | 11 | 26.6 | 0 | 21.7 | alto | 1 |
| 2023-03-25 | 6 | 242 | 36.2 | 23.8 | 39 | 11.9 | 27.7 | 0.3 | 24.9 | alto | 1 |
| 2023-03-26 | 14 | 235 | 35.8 | 23.3 | 33 | 12.7 | 23 | 0 | 28.5 | alto | 1 |
| 2023-03-27 | 1 | 6 | 35.3 | 23.1 | 32 | 13.8 | 30.2 | 0.8 | 28.1 | alto | 1 |
| 2023-03-28 | 0 | 0 | 36.1 | 24.2 | 37 | 12.6 | 29.5 | 0 | 27.7 | alto | 0 |
| 2023-03-29 | 0 | 0 | 30.7 | 24 | 62 | 13.2 | 29.2 | 6.4 | 3.8 | muy_bajo | 0 |
It is generated in your browser from this page’s data: one file per fire, aggregated by day and without individual hotspots.
Live widget for your story
It updates itself while the fire is still active and links to this page. Free, with the attribution shown at the bottom.
Sources for this page: GWIS (Copernicus), NASA FIRMS (VIIRS), ERA5 (ECMWF/Copernicus C3S) · Open-Meteo.com (CC BY 4.0), GHSL (JRC). Open-Meteo.com · How we build fire pages: methodology
- Burnt area
- 1,276ha
- GWIS perimeter (Copernicus)
- Duration
- 11days
- 17 Mar 2023 – 27 Mar 2023
- Municipalities hit
- 2
- chiefdoms
- Started on
- 17 Mar
- 2023
- Heat detections
- 40
- in a single hotspot: 141 MW
- Danger at start
- 26
- High · FWI index
- Average daily power
- 106MW
- detected power per day, on average
Where it burned
HOTSPOTS BY DAY
17 Mar27 Mar
27 Mar 2023
How it evolved, day by day
17 Mar
19 Mar
25 Mar
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
32km/h · peak gust
29%lowest humidity
It had gone 0 days without rain (1 mm or more) when it started. Rain came after the fire: 6.4 mm on 29 Mar.
This area had burned before
38% of the perimeter overlaps earlier fires recorded since 2016: 22 ha in 2016, 3 ha in 2017, 316 ha in 2019, 358 ha in 2021. Part of it burned more than once, so the yearly figures add up to more than the 491 ha that had burned before.
- 358 ha Nieni fire, March 2021 1,626 ha in total; the hectares shown are those it shares with this fire
- 316 ha Nieni fire, March 2019 1,336 ha in total; the hectares shown are those it shares with this fire
- 22 ha Nieni fire, March 2016 2,458 ha in total; the hectares shown are those it shares with this fire
- 3 ha Nieni fire, April 2017 1,405 ha in total; the hectares shown are those it shares with this fire
How big is it?
London boundary: geoBoundaries · Office for National Statistics (Open Government Licence v3.0).
Paris boundary: geoBoundaries · Institut national de l'information géographique et forestière (IGN-F) (Etalab Open License 2.0).
Madrid boundary: geoBoundaries · Open Data ESRI, IGN Central Registry of Cartography Area (CC BY 4.0).
Berlin boundary: geoBoundaries · Federal Agency for Cartography and Geodesy (dl-de/by-2-0).
This compares size, not location: both shapes are at the same scale, north up, centred on each other.
What happened to each town
-
Nieni where it started1,279 ha reached on 17 Mar0.6 %
-
0 ha reached on 18 Mar0.0 %
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 2025Built-up area0.98 ha
Residents≈ 350
Inside the perimeter there were about 0.98 hectares of built-up land and about 350 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) |
|---|---|---|---|---|---|
| 17 Mar | 35.3 °C | 33 % | 31 km/h | 0.0 mm | High 26 |
| 18 Mar | 34.6 °C | 32 % | 30 km/h | 0.0 mm | High 30 |
| 19 Mar | 34.5 °C | 34 % | 29 km/h | 0.1 mm | High 30 |
| 20 Mar | 35.2 °C | 29 % | 30 km/h | 0.0 mm | High 32 |
| 21 Mar | 34.5 °C | 40 % | 30 km/h | 0.0 mm | High 31 |
| 22 Mar | 33.6 °C | 43 % | 32 km/h | 1.1 mm | High 22 |
| 23 Mar | 33.6 °C | 50 % | 31 km/h | 2.8 mm | Low 9 |
| 24 Mar | 34.3 °C | 36 % | 27 km/h | 0.0 mm | High 22 |
| 25 Mar | 36.2 °C | 39 % | 28 km/h | 0.3 mm | High 25 |
| 26 Mar | 35.8 °C | 33 % | 23 km/h | 0.0 mm | High 28 |
| 27 Mar | 35.3 °C | 32 % | 30 km/h | 0.8 mm | High 28 |
| 28 Mar after | 36.1 °C | 37 % | 30 km/h | 0.0 mm | High 28 |
| 29 Mar after | 30.7 °C | 62 % | 29 km/h | 6.4 mm | Very low 4 |
Its twins: fires that started in the same weather
It started with an FWI of 25.9, a minimum humidity of 33% and rain the day before. Fires in the area that started in weather like this since 2016: 35.
FWI at the start
25.9
Minimum humidity
33 %
Days without rain
0
this fire
chosen twins
rest of the area
Almost identicalSimilar
Outlines of the closest twins
This fire · Nieni fire, 17 March 2023
1,276 ha
11 days
FWI 25.9
Min. humidity 33 %
Kunike fire, March 2020
1,157 ha
7 days
FWI 26.0
Min. humidity 32 %
15 km away, in 2020
First rain (1 mm or more) after it ended: 1.9 mm on 25 Mar.
Kunike fire, March 2020
3,593 ha
11 days
FWI 25.8
Min. humidity 32 %
23 km away, in 2020
First rain (1 mm or more) after it ended: 1.9 mm on 25 Mar.
Nieni fire, March 2021
1,626 ha
9 days
FWI 25.5
Min. humidity 32 %
2 km away, in 2021
First rain (1 mm or more) after it ended: 7.2 mm on 29 Mar.
Kafe Simiria fire, April 2024
1,333 ha
3 days
FWI 25.6
Min. humidity 34 %
58 km away, in 2024
First rain (1 mm or more) after it ended: none in the following ten days.
Safroko Limba fire, April 2022
1,412 ha
15 days
FWI 25.2
Min. humidity 34 %
73 km away, in 2022
First rain (1 mm or more) after it ended: 8.9 mm on 1 May.
What happened to them
- 11 days
- median duration
- 1,372 ha
- median area
- 100 %
- went past 1,000 ha
- 2.8 mm
- rain at the end (median; 34 of 35 had it)
It burned an area similar to its twins (1,276 ha against a median of 1,372 ha) and lasted 11 days, against 11 days.
In 1 of 35, 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 2.8 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
6.4 mmfirst rain
29 Mar2 days after it ended
32km/h · max. gust
It was considered over on 27 Mar, and on 29 Mar 6.4 mm fell. We do not know whether the rain or the firefighters put it out. Twins with rain when they ended: 34 of 35, with a median of 2.8 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.
Before and after, from space
Drag the line to compare the same ground before the fire and after it.
↔
Before · 10 Mar 2023
After · 3 Apr 2023
Sentinel-2 did not pass over on that day. Try another date, or use false colour, which is daily.
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 · CopernicusOn 26 March 2023 the air beside the fire reached 351 µg/m³ of PM2.5. That day averaged 176: 12 times the WHO daily guideline (15).
PM2.5 peak351 µg/m³
Days over the guideline8 days
PM10505 µg/m³
Optical depth1.89
WHO 15
22 Mar24 Mar26 Mar28 Mar
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 · 40Every 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
Frequently asked questions
- How long did the Nieni fire last?
- According to the heat detections seen by satellite inside the perimeter, it burned from 17 March 2023 to 27 March 2023 (11 days). The perimeter dates it from 24 March 2023 to 26 March 2023.
- How much area did it burn?
- The perimeter GWIS (Copernicus) rebuilt from heat detections is 1,276 hectares (12.8 km²). It is an estimate: official national figures may differ.
- Which municipalities burned?
- The fire entered 2 municipalities: Nieni (1,279 ha, 0.6 %); Sandor (0 ha, 0.0 %).
- What was the weather like?
- During the fire the temperature reached 36.2 °C, humidity dropped to 29 % and gusts hit 32 km/h. The fire danger index (FWI) reached 32, class High.
- Where does this data come from?
- From the GWIS (Copernicus) burnt perimeter, NASA FIRMS VIIRS hotspots and the administrative boundaries of Sierra Leone (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: 35. Their median duration was 11 days and their median area 1,372 ha; 100 % went past 1,000 ha. In 1 of 35, 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 2.8 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.
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.
- Last day with fire: 26 March 2023 → 27 March 2023.
- Start date: 24 March 2023 → 17 March 2023.
RSS Changes to this page With cross-checks and a citable version
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
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 24 March 2023 to 26 March 2023. 40 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.
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 ADM3 (Creative Commons Attribution 4.0 (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.