Burned area
satellite only3,317ha
Perimeter published by GWIS (Copernicus).
- Source
- GWIS (Copernicus)
- Date
- 26 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, 26 June 2021 Ust-Maysky Ulus
Out · last detection 5 Jul 2021, 04:53 UTC
The fire started on 26 June 2021 in Ust-Maysky Ulus, Russia, and satellites saw it burning for 10 days. Copernicus’s global GWIS system rebuilt a burnt perimeter of 3,317 hectares from heat detections, spread across a single municipality.
It is the 1243th largest in Sakha Republic since 2016 (of 1347 with a page). Number 528 in Russia in 2021, of 581.
Use this data
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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 only10days
26 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, 04:53 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 only26 Jun 2021
First day with fire seen by the satellites or the perimeter.
- Source
- GWIS (Copernicus) · NASA FIRMS · VIIRS
- Date
- 26 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 only361
VIIRS detections at 375 m. Most intense hotspot: 49 MW.
- Source
- NASA FIRMS · VIIRS (Suomi NPP)
- Date
- 26 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 only702MW
Total radiative power on 30 June 2021; hotspots that day: 65.
- 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
model11.1FWI · low
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
- 26 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
model33.8°C · 29% RH
High of 33.8 °C and minimum humidity of 29% on 3 July 2021; gusts of 37 km/h on 30 June 2021.
- Source
- weather model at the fire’s grid cell
- Date
- 26 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
- 3,317 ha
- Dates
- 26 Jun 2021 – 5 Jul 2021
- Name
- Ust-Maysky Ulus
- Official record
- —
Versioned permanent link
https://worldfires.org/en/fire/ust-maysky-ulus-2021-06-8?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-2021-06-8.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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 2021-06-26 | 7 | 20 | 27.5 | 11.9 | 34 | 12.7 | 35.3 | 0 | 11.1 | bajo | 1 |
| 2021-06-27 | 3 | 21 | 26.8 | 14 | 38 | 12.2 | 31.7 | 0 | 13.2 | moderado | 1 |
| 2021-06-28 | 15 | 70 | 30.2 | 10.9 | 31 | 6.8 | 20.2 | 0 | 14.5 | moderado | 1 |
| 2021-06-29 | 51 | 435 | 31.7 | 11.5 | 28 | 13 | 28.8 | 0 | 20.3 | moderado | 1 |
| 2021-06-30 | 65 | 702 | 30.6 | 13.2 | 24 | 14.9 | 36.7 | 0 | 23.9 | alto | 1 |
| 2021-07-01 | 46 | 466 | 31.5 | 11.9 | 26 | 13.6 | 27.4 | 0 | 24.2 | alto | 1 |
| 2021-07-02 | 47 | 222 | 31.7 | 10.4 | 27 | 10 | 18.4 | 0 | 22.9 | alto | 1 |
| 2021-07-03 | 84 | 595 | 33.8 | 11.9 | 29 | 12.5 | 22.7 | 0 | 25.4 | alto | 1 |
| 2021-07-04 | 10 | 81 | 31.7 | 14 | 41 | 12.9 | 28.1 | 0.2 | 23.2 | alto | 1 |
| 2021-07-05 | 33 | 230 | 30.9 | 17.8 | 38 | 11.1 | 29.5 | 0 | 22.8 | alto | 1 |
| 2021-07-06 | 0 | 0 | 22.1 | 14.5 | 69 | 8.7 | 27 | 7.7 | 0.3 | 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
- 3,317ha
- GWIS perimeter (Copernicus)
- Duration
- 10days
- 26 Jun 2021 – 5 Jul 2021
- Municipalities hit
- 1
- districts
- Started on
- 26 Jun
- 2021
- Heat detections
- 361
- in a single hotspot: 49 MW
- Danger at start
- 11
- Low · FWI index
- Average daily power
- 284MW
- detected power per day, on average
Where it burned
HOTSPOTS BY DAY
26 Jun5 Jul
5 Jul 2021
How it evolved, day by day
26 Jun
28 Jun
30 Jun
2 Jul
4 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
34°high
37km/h · peak gust
24%lowest humidity
It had gone 0 days without rain (1 mm or more) when it started. Rain came after the fire: 7.7 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 started3,164 ha reached on 26 Jun0.0 %
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 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) |
|---|---|---|---|---|---|
| 26 Jun | 27.5 °C | 34 % | 35 km/h | 0.0 mm | Low 11 |
| 27 Jun | 26.8 °C | 38 % | 32 km/h | 0.0 mm | Moderate 13 |
| 28 Jun | 30.2 °C | 31 % | 20 km/h | 0.0 mm | Moderate 14 |
| 29 Jun | 31.7 °C | 28 % | 29 km/h | 0.0 mm | Moderate 20 |
| 30 Jun | 30.6 °C | 24 % | 37 km/h | 0.0 mm | High 24 |
| 1 Jul | 31.5 °C | 26 % | 27 km/h | 0.0 mm | High 24 |
| 2 Jul | 31.7 °C | 27 % | 18 km/h | 0.0 mm | High 23 |
| 3 Jul | 33.8 °C | 29 % | 23 km/h | 0.0 mm | High 25 |
| 4 Jul | 31.7 °C | 41 % | 28 km/h | 0.2 mm | High 23 |
| 5 Jul | 30.9 °C | 38 % | 30 km/h | 0.0 mm | High 23 |
| 6 Jul after | 22.1 °C | 69 % | 27 km/h | 7.7 mm | Very low 0 |
Its twins: fires that started in the same weather
It started with an FWI of 11.1, a minimum humidity of 34% and rain the day before. Fires in the area that started in weather like this since 2017: 34.
FWI at the start
11.1
Minimum humidity
34 %
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, 26 June 2021
3,317 ha
10 days
FWI 11.1
Min. humidity 34 %
Aldansky Ulus fire, August 2024
3,464 ha
5 days
FWI 11.7
Min. humidity 36 %
102 km away, in 2024
First rain (1 mm or more) after it ended: 6.9 mm on 14 Aug.
Ust-Maysky Ulus fire, July 2017
5,460 ha
9 days
FWI 12.4
Min. humidity 34 %
229 km away, in 2017
First rain (1 mm or more) after it ended: 24.2 mm on 17 Jul.
Ayano-Maysky Rayon fire, June 2017
3,759 ha
12 days
FWI 10.9
Min. humidity 35 %
181 km away, in 2017
First rain (1 mm or more) after it ended: 3.9 mm on 12 Jul.
Aldansky Ulus fire, September 2020
3,561 ha
9 days
FWI 11.5
Min. humidity 32 %
60 km away, in 2020
First rain (1 mm or more) after it ended: none in the following ten days.
Aldansky Ulus fire, July 2019
3,167 ha
12 days
FWI 13.3
Min. humidity 34 %
137 km away, in 2019
First rain (1 mm or more) after it ended: 15.7 mm on 4 Aug.
What happened to them
- 13 days
- median duration
- 6,656 ha
- median area
- 35 %
- went past 10,000 ha
- 5.3 mm
- rain at the end (median; 32 of 34 had it)
It stayed below its twins: 3,317 ha against a median of 6,656 ha. It lasted 10 days, against 13 days.
In 2 of 34, 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 5.3 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
7.7 mmfirst rain
6 Julthe day after it ended
37km/h · max. gust
It was considered over on 5 Jul, and on 6 Jul 7.7 mm fell. We do not know whether the rain or the firefighters put it out. Twins with rain when they ended: 32 of 34, with a median of 5.3 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 · 19 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 · 361Every 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
- 25,666 haUst-Maysky UlusJune 2019 · 16 days · 14 km away
- 4,227 haUst-Maysky Ulus7 July 2018 · 7 days · 18 km away
- 4,439 haUst-Maysky Ulus28 June 2021 · 8 days · 23 km away
- 11,320 haUst-Maysky Ulus26 June 2024 · 19 days · 25 km away
- 4,763 haUst-Maysky Ulus29 June 2021 · 7 days · 29 km away
- 4,382 haUst-Maysky Ulus27 July 2023 · 6 days · 30 km away
Frequently asked questions
- How long did the Ust-Maysky Ulus fire last?
- GWIS (Copernicus) dates it between 26 June 2021 and 5 July 2021: 10 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 3,317 hectares (33.2 km²). It is an estimate: official national figures may differ.
- Which municipalities burned?
- The fire only entered Ust-Maysky Ulus (3,164 ha, 0.0 %).
- What was the weather like?
- During the fire the temperature reached 33.8 °C, humidity dropped to 24 % and gusts hit 37 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: 34. Their median duration was 13 days and their median area 6,656 ha; 35 % went past 10,000 ha. In 2 of 34, 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 5.3 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. 361 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.