Burned area
satellite only415ha
Perimeter published by NIFC WFIGS.
- Source
- NIFC WFIGS
- Date
- 2 Sept 2025 – 3 Sept 2025
+− cross-check
No official record is matched to this page to compare it with.
US · United States · –
Tuolumne fire, 2 September 2025 Tuolumne
Out · last detection 3 Sept 2025, 21:26 UTC
The fire started on 2 September 2025 in Tuolumne, United States, and satellites saw it burning for 2 days. United States agencies (MTBS / NIFC) mapped an official burnt perimeter of 415 hectares, spread across a single county.
It is the 434th largest in California since 2016 (of 442 with a page). Number 321 in United States in 2025, of 325.
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 only2days
2 Sept 2025 to 3 Sept 2025: first and last day with fire on the page.
- Source
- NIFC WFIGS · NASA FIRMS · VIIRS
- Date
- last detection: 3 Sept 2025, 21:26 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 only2 Sept 2025
First day with fire seen by the satellites or the perimeter.
- Source
- NIFC WFIGS · NASA FIRMS · VIIRS
- Date
- 2 Sept 2025
+− cross-check
No official record is matched to this page, so the alert time and the cause are not known here.
Hotspots
satellite only41
VIIRS detections at 375 m. Most intense hotspot: 53 MW.
- Source
- NASA FIRMS · VIIRS (Suomi NPP)
- Date
- 2 Sept 2025 – 3 Sept 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 only352MW
Total radiative power on 2 September 2025; hotspots that day: 15.
- Source
- NASA FIRMS · VIIRS (FRP)
- Date
- 2 Sept 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
model52.5FWI · extreme
Fire Weather Index (Canadian system) computed by WorldFires for the day the fire started. Consecutive days without rain before: 60.
- Source
- WorldFires calculation (Canadian FWI system)
- Date
- 2 Sept 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
model38.7°C · 18% RH
High of 38.7 °C and minimum humidity of 18% on 2 September 2025; gusts of 42 km/h on 2 September 2025.
- Source
- weather model at the fire’s grid cell
- Date
- 2 Sept 2025 – 3 Sept 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 weatherWeather and FWI computed from the ERA5 reanalysis
-
· reconstructed GHSLPopulation and built-up area computed
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
- 415 ha
- Dates
- 2 Sept 2025 – 3 Sept 2025
- Name
- Tuolumne
- Official record
- —
Versioned permanent link
https://worldfires.org/en/fire/tuolumne-2025-09?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 tuolumne-2025-09.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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 2025-09-02 | 15 | 352 | 38.7 | 22.3 | 18 | 15.2 | 41.8 | 0.5 | 52.5 | extremo | 1 |
| 2025-09-03 | 26 | 88 | 34.8 | 19.4 | 29 | 15.5 | 33.1 | 0 | 43.6 | muy_alto | 1 |
| 2025-09-04 | 0 | 0 | 32.8 | 19.1 | 30 | 16.3 | 35.3 | 0 | 46.4 | muy_alto | 0 |
| 2025-09-05 | 0 | 0 | 31.2 | 16 | 29 | 13.8 | 31.3 | 0 | 38.6 | muy_alto | 0 |
| 2025-09-06 | 0 | 0 | 30.9 | 16.9 | 31 | 14.9 | 32.4 | 0 | 37.3 | alto | 0 |
| 2025-09-07 | 0 | 0 | 30 | 14.7 | 26 | 12.1 | 29.9 | 0 | 40.1 | muy_alto | 0 |
| 2025-09-08 | 0 | 0 | 29.6 | 16.3 | 32 | 11.5 | 32.4 | 0 | 37.6 | alto | 0 |
| 2025-09-09 | 0 | 0 | 26.5 | 17.9 | 38 | 13.6 | 32.8 | 0.1 | 30.6 | alto | 0 |
| 2025-09-10 | 0 | 0 | 25.2 | 15.4 | 42 | 11.8 | 29.9 | 0.2 | 25.9 | alto | 0 |
| 2025-09-11 | 0 | 0 | 25.6 | 15.3 | 46 | 14.3 | 28.8 | 0 | 26.2 | alto | 0 |
| 2025-09-12 | 0 | 0 | 28.4 | 15 | 37 | 15.4 | 32 | 0 | 30.2 | alto | 0 |
| 2025-09-13 | 0 | 0 | 29.3 | 15.9 | 38 | 15 | 32.8 | 0 | 30.3 | alto | 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: NIFC WFIGS, 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
- 415ha
- official perimeter (MTBS / NIFC)
- Duration
- ≈ 2days
- 2 Sept 2025 – 3 Sept 2025
- Counties hit
- 1
- counties
- Started on
- 2 Sept
- 2025
- Heat detections
- 41
- in a single hotspot: 53 MW
- Danger at start
- 52
- Extreme · FWI index
- Average daily power
- 220MW
- detected power per day, on average
Where it burned
HOTSPOTS BY DAY
2 Sept3 Sept
3 Sept 2025
How it evolved, day by day
2 Sept
3 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
39°high
42km/h · peak gust
18%lowest humidity
It had gone more than two months without rain (1 mm or more) when it started.
This area had burned before
No earlier perimeters overlap this fire since 2016, when the satellite record begins.
What happened to each county
-
Tuolumne where it started410 ha reached on 2 Sept0.1 %
Burnt area inside each county, 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.
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)
Started with Extreme FWI: 36 % of the area in United States 60 days without rain: 7.0 % of the area in United States
| Day | High | Min. humidity | Peak gust | Rain | Danger (FWI) |
|---|---|---|---|---|---|
| 2 Sept | 38.7 °C | 18 % | 42 km/h | 0.5 mm | Extreme 52 |
| 3 Sept | 34.8 °C | 29 % | 33 km/h | 0.0 mm | Very high 44 |
| 4 Sept after | 32.8 °C | 30 % | 35 km/h | 0.0 mm | Very high 46 |
| 5 Sept after | 31.2 °C | 29 % | 31 km/h | 0.0 mm | Very high 39 |
| 6 Sept after | 30.9 °C | 31 % | 32 km/h | 0.0 mm | High 37 |
| 7 Sept after | 30.0 °C | 26 % | 30 km/h | 0.0 mm | Very high 40 |
| 8 Sept after | 29.6 °C | 32 % | 32 km/h | 0.0 mm | High 38 |
| 9 Sept after | 26.5 °C | 38 % | 33 km/h | 0.1 mm | High 31 |
| 10 Sept after | 25.2 °C | 42 % | 30 km/h | 0.2 mm | High 26 |
| 11 Sept after | 25.6 °C | 46 % | 29 km/h | 0.0 mm | High 26 |
| 12 Sept after | 28.4 °C | 37 % | 32 km/h | 0.0 mm | High 30 |
| 13 Sept after | 29.3 °C | 38 % | 33 km/h | 0.0 mm | High 30 |
Its twins: fires that started in the same weather
It started with an FWI of 52.5, a minimum humidity of 18% and more than two months without rain. Fires in the area that started in weather like this since 2016: 26.
FWI at the start
52.5
Minimum humidity
18 %
Days without rain
60+
this fire
chosen twins
rest of the area
Almost identicalSimilar
Outlines of the closest twins
This fire · Tuolumne fire, 2 September 2025
415 ha
2 days
FWI 52.5
Min. humidity 18 %
Hennessey Fire, August 2020
127,077 ha
16 days
FWI 51.7
Min. humidity 19 %
190 km away, in 2020
First rain (1 mm or more) after it ended: none in the following ten days.
River Fire, August 2021
1,095 ha
2 days
FWI 50.9
Min. humidity 16 %
158 km away, in 2021
First rain (1 mm or more) after it ended: none in the following ten days.
Gann Fire, August 2026
4,184 ha
3 days
FWI 51.2
Min. humidity 22 %
49 km away, in 2026
First rain (1 mm or more) after it ended: none in the following ten days.
Mariposa fire, September 2019
445 ha
1 day
FWI 50.0
Min. humidity 14 %
32 km away, in 2019
First rain (1 mm or more) after it ended: none in the following ten days.
Mineral Fire, July 2020
12,104 ha
8 days
FWI 53.5
Min. humidity 16 %
180 km away, in 2020
First rain (1 mm or more) after it ended: none in the following ten days.
What happened to them
- 3 days
- median duration
- 1,122 ha
- median area
- 58 %
- went past 1,000 ha
- 5.3 mm
- rain at the end (median; 4 of 26 had it)
It stayed below its twins: 415 ha against a median of 1,122 ha. It lasted 2 days, against 3 days.
In 22 of 26, 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
—first rain
—no rain in ten days
42km/h · max. gust
It was considered over on 3 Sept, and not even 1 mm fell in the following ten days: it went out without rain. Twins with rain when they ended: 4 of 26, 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 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 · 26 Aug 2025
After · 10 Sept 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 3 September 2025 the air beside the fire reached 34 µg/m³ of PM2.5. That day averaged 24: 1.6 times the WHO daily guideline (15).
PM2.5 peak34 µg/m³
Days over the guideline3 days
PM1045 µg/m³
Optical depth0.36
WHO 15
31 Aug2 Sept4 Sept6 Sept
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 · 41Every 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 Tuolumne fire last?
- The official perimeter only gives the start date (2 September 2025). The end comes from the heat detections inside the perimeter: it burned until 3 September 2025 (2 days from 2 September 2025), the last day with detections before more than 10 days in a row without any, so it is approximate.
- How much area did it burn?
- The official perimeter published by United States agencies (MTBS / NIFC) is 415 hectares (4.2 km²). Other tallies, such as daily incident reports, may give slightly different figures.
- Which counties burned?
- The fire only entered Tuolumne (410 ha, 0.1 %).
- What was the weather like?
- During the fire the temperature reached 38.7 °C, humidity dropped to 18 % and gusts hit 42 km/h. The fire danger index (FWI) reached 52, class Extreme.
- Where does this data come from?
- From the official burnt perimeter of United States agencies (MTBS / NIFC, public domain), NASA FIRMS VIIRS hotspots and the administrative boundaries of United States. 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: 26. Their median duration was 3 days and their median area 1,122 ha; 58 % went past 1,000 ha. In 22 of 26, 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: 911 · Emergency number and official warnings
- NIFC · National Interagency Fire Center ↗
- InciWeb · Incident Information System ↗
- MTBS · Monitoring Trends in Burn Severity ↗
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: NIFC WFIGS (United States), official.
- The official perimeter has no end date: the end is the last day with VIIRS detections inside the perimeter before a gap of more than 10 days (150 days at most), so it is approximate. 41 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 is official and in the public domain. For past years it comes from MTBS (Monitoring Trends in Burn Severity), run by the U.S. Geological Survey and the USDA Forest Service, which map it on Landsat and Sentinel-2 imagery. For the current and last year it comes from WFIGS at the National Interagency Fire Center (NIFC): incident perimeters mapped by fire crews, aircraft and imagery. Heat detections come from the VIIRS sensors aboard Suomi-NPP and NOAA-20, distributed by NASA FIRMS at 375 m resolution. County boundaries come from geoBoundaries ADM2 (Public Domain). The area per county is computed by WorldFires by crossing the perimeter with those boundaries, so it may differ slightly from official figures.