Burned area
satellite only15,026ha
Perimeter published by GWIS (Copernicus).
- Source
- GWIS (Copernicus)
- Date
- 23 Jun 2021 – 5 Jul 2021
+− cross-check
No official record is matched to this page to compare it with.
RU · Russia · –
Ust-Maysky Ulus fire, 23 June 2021 Ust-Maysky Ulus
Out · last detection 5 Jul 2021, 17:01 UTC
The fire started on 23 June 2021 in Ust-Maysky Ulus, Russia, and satellites saw it burning for 13 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 15,026 hectares from heat detections, spread across a single municipality.
It is the 317th largest in Sakha Republic since 2016 (of 1347 with a page). Number 122 in Russia in 2021, of 581.
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 only13days
23 Jun 2021 to 5 Jul 2021: first and last day with fire on the page.
- Source
- GWIS (Copernicus) · NASA FIRMS · VIIRS
- Date
- last detection: 5 Jul 2021, 17:01 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 only23 Jun 2021
First day with fire seen by the satellites or the perimeter.
- Source
- GWIS (Copernicus) · NASA FIRMS · VIIRS
- Date
- 23 Jun 2021
+− cross-check
No official record is matched to this page, so the alert time and the cause are not known here.
Hotspots
satellite only2,122
VIIRS detections at 375 m. Most intense hotspot: 256 MW.
- Source
- NASA FIRMS · VIIRS (Suomi NPP)
- Date
- 23 Jun 2021 – 5 Jul 2021
+− 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 only6,940MW
Total radiative power on 30 June 2021; hotspots that day: 327.
- Source
- NASA FIRMS · VIIRS (FRP)
- Date
- 30 Jun 2021
+− 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
model6.3FWI · low
Fire Weather Index (Canadian system) computed by WorldFires for the day the fire started. Consecutive days without rain before: 1.
- Source
- WorldFires calculation (Canadian FWI system)
- Date
- 23 Jun 2021, 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
model31.6°C · 30% RH
High of 31.6 °C and minimum humidity of 30% on 3 July 2021; gusts of 35 km/h on 30 June 2021.
- Source
- weather model at the fire’s grid cell
- Date
- 23 Jun 2021 – 5 Jul 2021
- 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
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
- 15,026 ha
- Dates
- 23 Jun 2021 – 5 Jul 2021
- Name
- Ust-Maysky Ulus
- Official record
- —
Versioned permanent link
https://worldfires.org/en/fire/ust-maysky-ulus-2021-06-4?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 ust-maysky-ulus-2021-06-4.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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 2021-06-23 | 9 | 26 | 23 | 11 | 43 | 13.3 | 34.2 | 1.6 | 6.3 | bajo | 1 |
| 2021-06-24 | 11 | 35 | 21.5 | 12.1 | 54 | 11.4 | 20.5 | 2.2 | 3 | muy_bajo | 1 |
| 2021-06-25 | 14 | 98 | 26.3 | 8.9 | 36 | 10.6 | 28.1 | 0 | 9.5 | bajo | 1 |
| 2021-06-26 | 31 | 297 | 26.7 | 10.2 | 32 | 10.2 | 27 | 0 | 15 | moderado | 1 |
| 2021-06-27 | 7 | 14 | 27.4 | 10.9 | 31 | 6.8 | 22.7 | 0 | 15.8 | moderado | 1 |
| 2021-06-28 | 123 | 814 | 29.5 | 10.5 | 29 | 6.6 | 18 | 0 | 17.8 | moderado | 1 |
| 2021-06-29 | 359 | 6,382 | 29.8 | 9.6 | 25 | 12.2 | 31.7 | 0 | 23.3 | alto | 1 |
| 2021-06-30 | 327 | 6,940 | 29 | 10.5 | 25 | 13.1 | 34.9 | 0 | 24.7 | alto | 1 |
| 2021-07-01 | 224 | 3,945 | 29.8 | 9.4 | 24 | 9.1 | 27.7 | 0 | 23.5 | alto | 1 |
| 2021-07-02 | 142 | 1,455 | 29.9 | 8.6 | 28 | 5.9 | 11.2 | 0 | 22.3 | alto | 1 |
| 2021-07-03 | 279 | 2,269 | 31.6 | 10.7 | 30 | 10.4 | 28.4 | 0 | 25.8 | alto | 1 |
| 2021-07-04 | 401 | 5,022 | 30.6 | 11.8 | 30 | 12.6 | 28.8 | 0 | 28 | alto | 1 |
| 2021-07-05 | 195 | 5,088 | 29.6 | 14.9 | 42 | 9.2 | 26.6 | 0.8 | 16.8 | moderado | 1 |
| 2021-07-06 | 0 | 0 | 18.8 | 13.6 | 78 | 8.2 | 22.3 | 8.5 | 0 | 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
- 15,026ha
- GWIS perimeter (Copernicus)
- Duration
- 13days
- 23 Jun 2021 – 5 Jul 2021
- Municipalities hit
- 1
- districts
- Started on
- 23 Jun
- 2021
- Heat detections
- 2,122
- in a single hotspot: 256 MW
- Danger at start
- 6
- Low · FWI index
- Average daily power
- 2.5GW
- detected power per day, on average
Where it burned
HOTSPOTS BY DAY
23 Jun5 Jul
5 Jul 2021
How it evolved, day by day
23 Jun
26 Jun
30 Jun
5 Jul
Fire radiative power detected each day, in megawatts, and number of hotspots. The magenta bar marks the peak day.
The weather it burned in
32°high
35km/h · peak gust
24%lowest humidity
It had gone one day without rain (1 mm or more) when it started. Rain came after the fire: 8.5 mm on 6 Jul.
This area had burned before
No earlier perimeters overlap this fire since 2016, when the satellite record begins.
How big is it?
London boundary: geoBoundaries · Office for National Statistics (Open Government Licence v3.0).
Moscow boundary: geoBoundaries · OpenStreetMap, Wambacher · © OpenStreetMap contributors (ODbL 1.0).
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).
This compares size, not location: both shapes are at the same scale, north up, centred on each other.
What happened to each town
-
Ust-Maysky Ulus where it started14,552 ha reached on 23 Jun0.2 %
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 2020Built-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) |
|---|---|---|---|---|---|
| 23 Jun | 23.0 °C | 43 % | 34 km/h | 1.6 mm | Low 6 |
| 24 Jun | 21.5 °C | 54 % | 20 km/h | 2.2 mm | Very low 3 |
| 25 Jun | 26.3 °C | 36 % | 28 km/h | 0.0 mm | Low 10 |
| 26 Jun | 26.7 °C | 32 % | 27 km/h | 0.0 mm | Moderate 15 |
| 27 Jun | 27.4 °C | 31 % | 23 km/h | 0.0 mm | Moderate 16 |
| 28 Jun | 29.5 °C | 29 % | 18 km/h | 0.0 mm | Moderate 18 |
| 29 Jun | 29.8 °C | 25 % | 32 km/h | 0.0 mm | High 23 |
| 30 Jun | 29.0 °C | 25 % | 35 km/h | 0.0 mm | High 25 |
| 1 Jul | 29.8 °C | 24 % | 28 km/h | 0.0 mm | High 24 |
| 2 Jul | 29.9 °C | 28 % | 11 km/h | 0.0 mm | High 22 |
| 3 Jul | 31.6 °C | 30 % | 28 km/h | 0.0 mm | High 26 |
| 4 Jul | 30.6 °C | 30 % | 29 km/h | 0.0 mm | High 28 |
| 5 Jul | 29.6 °C | 42 % | 27 km/h | 0.8 mm | Moderate 17 |
| 6 Jul after | 18.8 °C | 78 % | 22 km/h | 8.5 mm | Very low 0 |
Its twins: fires that started in the same weather
It started with an FWI of 6.3, a minimum humidity of 43% and 1 day without rain. Fires in the area that started in weather like this since 2017: 23.
FWI at the start
6.3
Minimum humidity
43 %
Days without rain
1
this fire
chosen twins
rest of the area
Almost identicalSimilar
Outlines of the closest twins
This fire · Ust-Maysky Ulus fire, 23 June 2021
15,026 ha
13 days
FWI 6.3
Min. humidity 43 %
Amginsky Ulus fire, September 2020
29,967 ha
15 days
FWI 8.1
Min. humidity 43 %
185 km away, in 2020
First rain (1 mm or more) after it ended: 1.1 mm on 29 Sept.
Tomponsky Ulus fire, July 2021
39,480 ha
18 days
FWI 7.6
Min. humidity 43 %
229 km away, in 2021
First rain (1 mm or more) after it ended: 8.3 mm on 16 Aug.
Ayano-Maysky Rayon fire, July 2022
55,955 ha
36 days
FWI 9.2
Min. humidity 43 %
184 km away, in 2022
First rain (1 mm or more) after it ended: 1.6 mm on 8 Aug.
Okhotsky Rayon fire, June 2022
6,173 ha
11 days
FWI 8.3
Min. humidity 42 %
174 km away, in 2022
First rain (1 mm or more) after it ended: 1.4 mm on 11 Jul.
Ust-Maysky Ulus fire, August 2022
6,079 ha
5 days
FWI 9.3
Min. humidity 45 %
85 km away, in 2022
First rain (1 mm or more) after it ended: 1.1 mm on 24 Aug.
What happened to them
- 16 days
- median duration
- 9,426 ha
- median area
- 48 %
- went past 10,000 ha
- 5.9 mm
- rain at the end (median; 23 of 23 had it)
It was 1.6 times larger than the median of its twins and lasted 13 days, against 16 days.
Only 9 of its 23 twins burned more. The weather on the first day does not explain everything: the wind in the following days, the fuel and the firefighting also count. All of them had rain in the ten days after the end: the first rainy day brought a median of 5.9 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
8.5 mmfirst rain
6 Julthe day after it ended
35km/h · max. gust
It was considered over on 5 Jul, and on 6 Jul 8.5 mm fell. We do not know whether the rain or the firefighters put it out. Twins with rain when they ended: 23 of 23, with a median of 5.9 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 2017.
- 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 · 16 Jun 2021
After · 12 Jul 2021
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.
Detections table · 2,122Every 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 Ust-Maysky Ulus fire last?
- GWIS (Copernicus) dates it between 23 June 2021 and 5 July 2021: 13 days 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 15,026 hectares (150.3 km²). It is an estimate: official national figures may differ.
- Which municipalities burned?
- The fire only entered Ust-Maysky Ulus (14,552 ha, 0.2 %).
- What was the weather like?
- During the fire the temperature reached 31.6 °C, humidity dropped to 24 % and gusts hit 35 km/h. The fire danger index (FWI) reached 28, class High.
- Where does this data come from?
- From the GWIS (Copernicus) burnt perimeter, NASA FIRMS VIIRS hotspots and the administrative boundaries of Russia (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 2017 with a similar FWI, humidity and dry spell: 23. Their median duration was 16 days and their median area 9,426 ha; 48 % went past 10,000 ha. Only 9 of its 23 twins burned more. The weather on the first day does not explain everything: the wind in the following days, the fuel and the firefighting also count. All of them had rain in the ten days after the end: the first rainy day brought a median of 5.9 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: 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: GWIS (Copernicus), rebuilt from heat detections rather than mapped on imagery.
- Dates from the perimeter: the VIIRS detections inside it did not change them. 2,122 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.
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 (Open Data Commons Open Database License 1.0). 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.