Burned area
satellite only103ha
Perimeter published by EFFIS (Copernicus).
- Source
- EFFIS (Copernicus)
- Date
- perimeter revised on 13 May 2025
+− cross-check
No official record is matched to this page to compare it with.
UA · Ukraine ·
Korosten fire, 21 April 2025 Коростенський район · Korosten
Out · last detection 21 Apr 2025, 11:50 UTC
The fire started on 21 April 2025 in Korosten, Ukraine, and satellites saw it burning for 1 day. Copernicus mapped a burnt perimeter of 103 hectares from satellite imagery, spread across a single municipality.
It is the 175th largest in Zhytomyr Oblast since 2016 (of 179 with a page). Number 1302 in Ukraine in 2025, of 1358.
The power measured by the satellite is low (10.2 MW in the strongest hotspot), more typical of grass or stubble burning, or a slow surface fire, than of a large crown fire.
Use this data
Compare with…
Use this data
Fire page data · version 2026-10-24matches 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 only1day
21 Apr 2025 to 21 Apr 2025: first and last day with fire on the page.
- Source
- EFFIS (Copernicus) · NASA FIRMS · VIIRS
- Date
- last detection: 21 Apr 2025, 11:50 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 only21 Apr 2025
First day with fire seen by the satellites or the perimeter.
- Source
- EFFIS (Copernicus) · NASA FIRMS · VIIRS
- Date
- 21 Apr 2025
+− cross-check
No official record is matched to this page, so the alert time and the cause are not known here.
Hotspots
satellite only4
VIIRS detections at 375 m. Most intense hotspot: 10 MW.
- Source
- NASA FIRMS · VIIRS (Suomi NPP)
- Date
- 21 Apr 2025 – 21 Apr 2025
+− 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 only23MW
Total radiative power on 21 April 2025; hotspots that day: 4.
- Source
- NASA FIRMS · VIIRS (FRP)
- Date
- 21 Apr 2025
+− 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
model16.7FWI · moderate
Fire Weather Index (Canadian system) computed by WorldFires for the day the fire started. Consecutive days without rain before: 10.
- Source
- WorldFires calculation (Canadian FWI system)
- Date
- 21 Apr 2025, 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
model26.2°C · 16% RH
High of 26.2 °C and minimum humidity of 16% on 21 April 2025; gusts of 28 km/h on 21 April 2025.
- Source
- weather model at the fire’s grid cell
- Date
- 21 Apr 2025 – 21 Apr 2025
- 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.
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 GHSLPopulation and built-up area computed
-
· reconstructed weatherWeather and FWI computed from the ERA5 reanalysis
-
· reconstructed perimeterEFFIS (Copernicus) revises the perimeter
What was saved on 24 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
- 103 ha
- Dates
- 21 Apr 2025 – 21 Apr 2025
- Name
- Korosten
- Official record
- —
Versioned permanent link
https://worldfires.org/en/fire/korosten-2025-04-4?v=2026-10-24A 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 korosten-2025-04-4.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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 2025-04-21 | 4 | 23 | 26.2 | 6.8 | 16 | 13.3 | 28.1 | 0 | 16.7 | moderado | 1 |
| 2025-04-22 | 0 | 0 | 26.3 | 8.7 | 17 | 14.1 | 27.7 | 0 | 18.4 | moderado | 0 |
| 2025-04-23 | 0 | 0 | 27.3 | 9 | 15 | 13.3 | 27.7 | 0 | 20 | moderado | 0 |
| 2025-04-24 | 0 | 0 | 25.4 | 10.9 | 28 | 13.3 | 28.1 | 1.2 | 11.2 | moderado | 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: EFFIS (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
- 103ha
- Copernicus perimeter
- Duration
- 1day
- 21 Apr 2025 – 21 Apr 2025
- Municipalities hit
- 1
- districts
- Started on
- 21 Apr
- 2025
- Heat detections
- 4
- in a single hotspot: 10 MW
- Danger at start
- 17
- Moderate · FWI index
- Average daily power
- 23MW
- detected power per day, on average
Where it burned
HOTSPOTS BY DAY
21 Apr21 Apr
How it evolved, day by day
21 Apr 2025 · 23 MW · 4
Fire radiative power detected each day, in megawatts, and number of hotspots. The magenta bar marks the peak day.
The weather it burned in
26°high
28km/h · peak gust
16%lowest humidity
It had gone 10 days without rain (1 mm or more) when it started. Rain came after the fire: 1.2 mm on 24 Apr.
This area had burned before
No earlier perimeters overlap this fire since 2016, when the satellite record begins.
What happened to each town
-
103 ha reached on 21 Apr0.1 %
Burnt area inside each municipality, from crossing the official 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.
What burned
- Agricultural areas58 %
- Mixed forest23 %
- Other natural land18 %
Land cover inside the perimeter as reported by Copernicus EFFIS (outside the Corine Land Cover area).
People and buildings inside the perimeter
GHSL 2025Built-up area< 0.1 ha
Residents< 20
Inside the perimeter there was no noticeable built-up land and almost nobody lived there (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) |
|---|---|---|---|---|---|
| 21 Apr | 26.2 °C | 16 % | 28 km/h | 0.0 mm | Moderate 17 |
| 22 Apr after | 26.3 °C | 17 % | 28 km/h | 0.0 mm | Moderate 18 |
| 23 Apr after | 27.3 °C | 15 % | 28 km/h | 0.0 mm | Moderate 20 |
| 24 Apr after | 25.4 °C | 28 % | 28 km/h | 1.2 mm | Moderate 11 |
Its twins: fires that started in the same weather
It started with an FWI of 16.7, a minimum humidity of 16% and 10 days without rain. Fires in the area that started in weather like this since 2020: 15.
FWI at the start
16.7
Minimum humidity
16 %
Days without rain
10
this fire
chosen twins
rest of the area
Almost identicalSimilar
Outlines of the closest twins
This fire · Korosten fire, 21 April 2025
103 ha
1 day
FWI 16.7
Min. humidity 16 %
Yemilchyne fire, April 2020
199 ha
1 day
FWI 15.8
Min. humidity 15 %
30 km away, in 2020
First rain (1 mm or more) after it ended: none in the following ten days.
Yemilchyne fire, April 2020
202 ha
4 days
FWI 15.4
Min. humidity 18 %
42 km away, in 2020
First rain (1 mm or more) after it ended: 2.2 mm on 14 Apr.
Pulyny fire, April 2020
1,303 ha
9 days
FWI 15.6
Min. humidity 18 %
37 km away, in 2020
First rain (1 mm or more) after it ended: 3.2 mm on 14 Apr.
Yemilchyne fire, April 2020
686 ha
5 days
FWI 15.0
Min. humidity 18 %
46 km away, in 2020
First rain (1 mm or more) after it ended: 2.0 mm on 14 Apr.
Olevsk fire, April 2020
123 ha
1 day
FWI 20.3
Min. humidity 16 %
81 km away, in 2020
First rain (1 mm or more) after it ended: 1.2 mm on 13 Apr.
What happened to them
- 5 days
- median duration
- 278 ha
- median area
- 27 %
- went past 1,000 ha
- 2.4 mm
- rain at the end (median; 14 of 15 had it)
It stayed below its twins: 103 ha against a median of 278 ha. It lasted 1 day, against 5 days.
In 1 of 15, 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 2.4 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
1.2 mmfirst rain
24 Apr3 days after it ended
28km/h · max. gust
It was considered over on 21 Apr, and on 24 Apr 1.2 mm fell. We do not know whether the rain or the firefighters put it out. Twins with rain when they ended: 14 of 15, with a median of 2.4 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 2020.
- 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 · 14 Apr 2025
After · 28 Apr 2025
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 23 April 2025 the air beside the fire reached 19 µg/m³ of PM2.5, but no daily average passed the WHO guideline (15).
PM2.5 peak19 µg/m³
Days over the guideline0 days
PM1028 µg/m³
Optical depth0.31
WHO 15
19 Apr21 Apr23 Apr
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 · 4Every 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
- 2,159 haLuhyny Лугинський район25 March 2020 · 7 days · 25 km away
- 1,617 haYemilchyne Ємільчинський район6 March 2025 · 3 days · 29 km away
- 1,160 haKhoroshiv Хорошівський районApril 2020 · 6 days · 30 km away
- 3,629 haYemilchyne Ємільчинський район24 March 2020 · 17 days · 31 km away
- 1,303 haPulyny Пулинський район5 April 2020 · 9 days · 37 km away
Frequently asked questions
- How long did the Korosten fire last?
- Copernicus dates it between 21 April 2025 and 21 April 2025: 1 day between the first and last image with fire.
- How much area did it burn?
- The perimeter Copernicus measured from satellite imagery is 103 hectares (1.0 km²). Official national figures may differ.
- Which municipalities burned?
- The fire only entered Korosten (103 ha, 0.1 %).
- Did the fire reach a town?
- The fire started in Korosten and came within 12.1 km of its centre. That is the distance from the perimeter, or the nearest hotspot, to the point marking the centre; it does not mean it entered the houses.
- What was the weather like?
- During the fire the temperature reached 26.2 °C, humidity dropped to 16 % and gusts hit 28 km/h. The fire danger index (FWI) reached 17, class Moderate.
- Where does this data come from?
- From the EFFIS (Copernicus) burnt perimeter, NASA FIRMS VIIRS hotspots and the administrative boundaries of Ukraine (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 2020 with a similar FWI, humidity and dry spell: 15. Their median duration was 5 days and their median area 278 ha; 27 % went past 1,000 ha. In 1 of 15, 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 2.4 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: 101 · 112 · 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.
No changes since 24 October 2026.
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: EFFIS (Copernicus), mapped on satellite imagery.
- Dates from the perimeter: the VIIRS detections inside it did not change them. 4 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 and land cover come from the Copernicus European Forest Fire Information System (EFFIS), measured on MODIS and Sentinel-2 imagery and published under CC BY 4.0. 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 slightly from each country’s official figure.