Burned area
satellite only8,808ha
Perimeter published by GWIS (Copernicus).
- Source
- GWIS (Copernicus)
- Date
- 22 Aug 2021 – 16 Sept 2021
+− cross-check
No official record is matched to this page to compare it with.
RU · Russia · –
Ust-Maysky Ulus fire, 22 August 2021 Ust-Maysky Ulus
Out · last detection 16 Sept 2021, 17:33 UTC
The fire started on 22 August 2021 in Ust-Maysky Ulus, Russia, and satellites saw it burning for 26 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 8,808 hectares from heat detections, spread across a single municipality.
It is the 526th largest in Sakha Republic since 2016 (of 1347 with a page). Number 190 in Russia in 2021, of 581.
Use this data
Compare with…
Use this data
Fire page data · version 2026-10-25matches 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 only26days
22 Aug 2021 to 16 Sept 2021: first and last day with fire on the page.
- Source
- GWIS (Copernicus) · NASA FIRMS · VIIRS
- Date
- last detection: 16 Sept 2021, 17:33 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 only22 Aug 2021
First day with fire seen by the satellites or the perimeter.
- Source
- GWIS (Copernicus) · NASA FIRMS · VIIRS
- Date
- 22 Aug 2021
+− cross-check
No official record is matched to this page, so the alert time and the cause are not known here.
Hotspots
satellite only1,322
VIIRS detections at 375 m. Most intense hotspot: 285 MW.
- Source
- NASA FIRMS · VIIRS (Suomi NPP)
- Date
- 22 Aug 2021 – 16 Sept 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 only5,153MW
Total radiative power on 3 September 2021; hotspots that day: 388.
- Source
- NASA FIRMS · VIIRS (FRP)
- Date
- 3 Sept 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
model22.5FWI · 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
- 22 Aug 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
model30.4°C · 38% RH
High of 30.4 °C and minimum humidity of 38% on 22 August 2021; gusts of 44 km/h on 27 August 2021.
- Source
- weather model at the fire’s grid cell
- Date
- 22 Aug 2021 – 16 Sept 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
-
logLast day with fire: 14 September 2021 → 16 September 2021.
-
· reconstructed weatherWeather and FWI computed from the ERA5 reanalysis
-
· reconstructed GHSLPopulation and built-up area computed
What was saved on 25 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
- 8,808 ha
- Dates
- 22 Aug 2021 – 16 Sept 2021
- Name
- Ust-Maysky Ulus
- Official record
- —
Versioned permanent link
https://worldfires.org/en/fire/ust-maysky-ulus-2021-08-8?v=2026-10-25A 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-2021-08-8.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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 2021-08-22 | 5 | 17 | 30.4 | 18.1 | 38 | 15.7 | 35.3 | 0 | 22.5 | alto | 1 |
| 2021-08-23 | 0 | 0 | 28 | 18.4 | 44 | 13.4 | 30.2 | 0 | 21.6 | alto | 1 |
| 2021-08-24 | 27 | 236 | 26.5 | 18.1 | 50 | 14.7 | 33.8 | 1.1 | 13.4 | moderado | 1 |
| 2021-08-25 | 0 | 0 | 20.1 | 14.5 | 75 | 11 | 25.9 | 2.5 | 2.9 | muy_bajo | 1 |
| 2021-08-26 | 8 | 15 | 21.6 | 12.7 | 37 | 9.4 | 26.6 | 0 | 7.2 | bajo | 1 |
| 2021-08-27 | 13 | 23 | 18.5 | 10.9 | 58 | 13 | 43.9 | 0.7 | 8.9 | bajo | 1 |
| 2021-08-28 | 0 | 0 | 10.9 | 7.1 | 55 | 14.1 | 31.7 | 0 | 10.7 | bajo | 1 |
| 2021-08-29 | 4 | 9 | 12.2 | 4.8 | 56 | 7.1 | 19.1 | 0 | 9.2 | bajo | 1 |
| 2021-08-30 | 34 | 232 | 18.1 | 0.9 | 39 | 6.8 | 18 | 0 | 12.7 | moderado | 1 |
| 2021-08-31 | 2 | 9 | 16.5 | 4.8 | 42 | 12 | 29.5 | 2.2 | 5.2 | muy_bajo | 1 |
| 2021-09-01 | 19 | 26 | 18.9 | 5.8 | 40 | 10.9 | 28.8 | 0 | 10 | bajo | 1 |
| 2021-09-02 | 113 | 607 | 21.3 | 3.4 | 37 | 7.9 | 16.9 | 0 | 14 | moderado | 1 |
| 2021-09-03 | 388 | 5,153 | 26.1 | 3.4 | 30 | 17.1 | 32.4 | 0 | 25.1 | alto | 1 |
| 2021-09-04 | 0 | 0 | 16 | 7.8 | 50 | 13.6 | 29.9 | 5.5 | 2 | muy_bajo | 1 |
| 2021-09-05 | 0 | 0 | 13 | 1.8 | 47 | 15.1 | 32.4 | 0.5 | 4.9 | muy_bajo | 1 |
| 2021-09-06 | 2 | 9 | 17.1 | -2.1 | 37 | 8.4 | 19.1 | 0 | 7.7 | bajo | 1 |
| 2021-09-07 | 2 | 8 | 19.5 | -1.1 | 27 | 7.3 | 17.3 | 0 | 13.5 | moderado | 1 |
| 2021-09-08 | 34 | 84 | 22.1 | 0.6 | 32 | 12.6 | 30.2 | 0 | 18.2 | moderado | 1 |
| 2021-09-09 | 59 | 225 | 17.1 | 0.6 | 30 | 10.8 | 27 | 0 | 17.7 | moderado | 1 |
| 2021-09-10 | 73 | 211 | 19.3 | -1.3 | 33 | 7.6 | 24.1 | 0 | 16.5 | moderado | 1 |
| 2021-09-11 | 125 | 379 | 19.6 | -2.3 | 32 | 8.7 | 20.2 | 0 | 17.4 | moderado | 1 |
| 2021-09-12 | 147 | 396 | 19.9 | -3.8 | 34 | 9.7 | 14 | 0 | 18.2 | moderado | 1 |
| 2021-09-13 | 217 | 928 | 21.8 | -1.9 | 32 | 11.6 | 15.5 | 0 | 19.7 | moderado | 1 |
| 2021-09-14 | 44 | 301 | 20 | 1.8 | 45 | 10.1 | 16.2 | 0.1 | 17.7 | moderado | 1 |
| 2021-09-15 | 1 | 1 | 18 | 2.4 | 48 | 8.7 | 16.6 | 1.1 | 8.1 | bajo | 1 |
| 2021-09-16 | 5 | 26 | 20.1 | 4.3 | 40 | 16.6 | 31.3 | 0 | 16.5 | moderado | 1 |
| 2021-09-17 | 0 | 0 | 14.8 | 5.2 | 52 | 18.2 | 37.1 | 18.1 | 0.4 | 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
- 8,808ha
- GWIS perimeter (Copernicus)
- Duration
- 26days
- 22 Aug 2021 – 16 Sept 2021
- Municipalities hit
- 1
- districts
- Started on
- 22 Aug
- 2021
- Heat detections
- 1,322
- in a single hotspot: 285 MW
- Danger at start
- 22
- High · FWI index
- Average daily power
- 424MW
- detected power per day, on average
Where it burned
HOTSPOTS BY DAY
22 Aug16 Sept
16 Sept 2021
How it evolved, day by day
22 Aug
30 Aug
3 Sept
11 Sept
16 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
30°high
44km/h · peak gust
27%lowest humidity
It had gone 0 days without rain (1 mm or more) when it started. Rain came after the fire: 18.1 mm on 17 Sept.
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 started8,729 ha reached on 22 Aug0.1 %
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) |
|---|---|---|---|---|---|
| 22 Aug | 30.4 °C | 38 % | 35 km/h | 0.0 mm | High 22 |
| 23 Aug | 28.0 °C | 44 % | 30 km/h | 0.0 mm | High 22 |
| 24 Aug | 26.5 °C | 50 % | 34 km/h | 1.1 mm | Moderate 13 |
| 25 Aug | 20.1 °C | 75 % | 26 km/h | 2.5 mm | Very low 3 |
| 26 Aug | 21.6 °C | 37 % | 27 km/h | 0.0 mm | Low 7 |
| 27 Aug | 18.5 °C | 58 % | 44 km/h | 0.7 mm | Low 9 |
| 28 Aug | 10.9 °C | 55 % | 32 km/h | 0.0 mm | Low 11 |
| 29 Aug | 12.2 °C | 56 % | 19 km/h | 0.0 mm | Low 9 |
| 30 Aug | 18.1 °C | 39 % | 18 km/h | 0.0 mm | Moderate 13 |
| 31 Aug | 16.5 °C | 42 % | 30 km/h | 2.2 mm | Very low 5 |
| 1 Sept | 18.9 °C | 40 % | 29 km/h | 0.0 mm | Low 10 |
| 2 Sept | 21.3 °C | 37 % | 17 km/h | 0.0 mm | Moderate 14 |
| 3 Sept | 26.1 °C | 30 % | 32 km/h | 0.0 mm | High 25 |
| 4 Sept | 16.0 °C | 50 % | 30 km/h | 5.5 mm | Very low 2 |
| 5 Sept | 13.0 °C | 47 % | 32 km/h | 0.5 mm | Very low 5 |
| 6 Sept | 17.1 °C | 37 % | 19 km/h | 0.0 mm | Low 8 |
| 7 Sept | 19.5 °C | 27 % | 17 km/h | 0.0 mm | Moderate 14 |
| 8 Sept | 22.1 °C | 32 % | 30 km/h | 0.0 mm | Moderate 18 |
| 9 Sept | 17.1 °C | 30 % | 27 km/h | 0.0 mm | Moderate 18 |
| 10 Sept | 19.3 °C | 33 % | 24 km/h | 0.0 mm | Moderate 16 |
| 11 Sept | 19.6 °C | 32 % | 20 km/h | 0.0 mm | Moderate 17 |
| 12 Sept | 19.9 °C | 34 % | 14 km/h | 0.0 mm | Moderate 18 |
| 13 Sept | 21.8 °C | 32 % | 16 km/h | 0.0 mm | Moderate 20 |
| 14 Sept | 20.0 °C | 45 % | 16 km/h | 0.1 mm | Moderate 18 |
| 15 Sept | 18.0 °C | 48 % | 17 km/h | 1.1 mm | Low 8 |
| 16 Sept | 20.1 °C | 40 % | 31 km/h | 0.0 mm | Moderate 16 |
| 17 Sept after | 14.8 °C | 52 % | 37 km/h | 18.1 mm | Very low 0 |
Its twins: fires that started in the same weather
It started with an FWI of 22.5, a minimum humidity of 38% and rain the day before. Fires in the area that started in weather like this since 2017: 19.
FWI at the start
22.5
Minimum humidity
38 %
Days without rain
0
this fire
chosen twins
rest of the area
Almost identicalSimilar
Outlines of the closest twins
This fire · Ust-Maysky Ulus fire, 22 August 2021
8,808 ha
26 days
FWI 22.5
Min. humidity 38 %
Ayano-Maysky Rayon fire, July 2023
3,058 ha
19 days
FWI 20.5
Min. humidity 38 %
197 km away, in 2023
First rain (1 mm or more) after it ended: 4.9 mm on 14 Aug.
Ust-Maysky Ulus fire, July 2023
131,929 ha
32 days
FWI 23.2
Min. humidity 41 %
120 km away, in 2023
First rain (1 mm or more) after it ended: 4.4 mm on 14 Aug.
Ust-Maysky Ulus fire, August 2023
3,444 ha
6 days
FWI 25.8
Min. humidity 39 %
92 km away, in 2023
First rain (1 mm or more) after it ended: 4.2 mm on 14 Aug.
Ust-Maysky Ulus fire, June 2021
43,982 ha
23 days
FWI 21.3
Min. humidity 35 %
69 km away, in 2021
First rain (1 mm or more) after it ended: 16.8 mm on 16 Jul.
Aldansky Ulus fire, June 2017
4,640 ha
10 days
FWI 20.4
Min. humidity 38 %
203 km away, in 2017
First rain (1 mm or more) after it ended: 2.5 mm on 5 Jul.
What happened to them
- 19 days
- median duration
- 8,734 ha
- median area
- 47 %
- went past 10,000 ha
- 4.4 mm
- rain at the end (median; 19 of 19 had it)
It burned an area similar to its twins (8,808 ha against a median of 8,734 ha) and lasted 26 days, against 19 days.
All of them had rain in the ten days after the end: the first rainy day brought a median of 4.4 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
18.1 mmfirst rain
17 Septthe day after it ended
44km/h · max. gust
It was considered over on 16 Sept, and on 17 Sept 18.1 mm fell. We do not know whether the rain or the firefighters put it out. Twins with rain when they ended: 19 of 19, with a median of 4.4 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 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 · 15 Aug 2021
After · 23 Sept 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 · 1,322Every 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
- 4,508 haUst-Maysky Ulus4 July 2022 · 7 days · 10 km away
- 7,185 haUst-Maysky UlusSeptember 2021 · 10 days · 14 km away
- 3,434 haUst-Maysky Ulus24 July 2023 · 8 days · 15 km away
- 3,632 haUst-Maysky Ulus21 August 2021 · 4 days · 16 km away
- 31,907 haUst-Maysky Ulus25 July 2022 · 15 days · 22 km away
- 6,079 haUst-Maysky UlusAugust 2022 · 5 days · 23 km away
Frequently asked questions
- How long did the Ust-Maysky Ulus fire last?
- According to the heat detections seen by satellite inside the perimeter, it burned from 22 August 2021 to 16 September 2021 (26 days). The perimeter dates it from 22 August 2021 to 14 September 2021.
- How much area did it burn?
- The perimeter GWIS (Copernicus) rebuilt from heat detections is 8,808 hectares (88.1 km²). It is an estimate: official national figures may differ.
- Which municipalities burned?
- The fire only entered Ust-Maysky Ulus (8,729 ha, 0.1 %).
- What was the weather like?
- During the fire the temperature reached 30.4 °C, humidity dropped to 27 % and gusts hit 44 km/h. The fire danger index (FWI) reached 25, 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: 19. Their median duration was 19 days and their median area 8,734 ha; 47 % went past 10,000 ha. All of them had rain in the ten days after the end: the first rainy day brought a median of 4.4 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: 112 · Emergency number and official warnings
Satellite cross-check
History of this page · 1 Changes in area, dates, name, official record or merged pages, compared every night since 24 October 2026.
- Last day with fire: 14 September 2021 → 16 September 2021.
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 22 August 2021 to 14 September 2021. 1,322 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.