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Caldor Fire, August 2021 El Dorado, Amador, Alpine

Out · last detection 5 Oct 2021, 09:56 UTC

The fire started on 15 August 2021 in El Dorado, United States, and satellites saw it burning for 52 days. United States agencies (MTBS / NIFC) mapped an official burnt perimeter of 91,758 hectares, spread across 3 counties.

It is the 11th largest in California since 2016 (of 442 with a page). Number 4 in United States in 2021, of 385.

Compare with…

Suggestions: Caples · 2019Fork · 2020

Burnt area
91,758ha
official perimeter (MTBS / NIFC)
Duration
≈ 52days
15 Aug 2021 – 5 Oct 2021
Counties hit
3
counties
Started on
15 Aug
2021
Heat detections
20,371
in a single hotspot: 2,226 MW
Danger at start
36
High · FWI index
Average daily power
10.5GW
detected power per day, on average

Where it burned

HOTSPOTS BY DAY 15 Aug5 Oct
5 Oct 2021

How it evolved, day by day

15 Aug 2021 · 603 MW · 22 16 Aug 2021 · 7,187 MW · 110 17 Aug 2021 · 85,430 MW · 962 18 Aug 2021 · 23,273 MW · 1802 19 Aug 2021 · 16,537 MW · 908 20 Aug 2021 · 19,522 MW · 1008 21 Aug 2021 · 58,767 MW · 1114 22 Aug 2021 · 14,219 MW · 980 23 Aug 2021 · 18,774 MW · 966 24 Aug 2021 · 17,994 MW · 979 25 Aug 2021 · 16,563 MW · 957 26 Aug 2021 · 28,214 MW · 1282 27 Aug 2021 · 9,533 MW · 788 28 Aug 2021 · 18,271 MW · 700 29 Aug 2021 · 30,040 MW · 950 30 Aug 2021 · 33,646 MW · 1198 31 Aug 2021 · 41,570 MW · 1622 1 Sept 2021 · 27,206 MW · 1176 2 Sept 2021 · 8,250 MW · 574 3 Sept 2021 · 2,723 MW · 452 4 Sept 2021 · 1,806 MW · 294 5 Sept 2021 · 1,228 MW · 214 6 Sept 2021 · 1,221 MW · 227 7 Sept 2021 · 2,236 MW · 179 8 Sept 2021 · 1,052 MW · 230 9 Sept 2021 · 415 MW · 58 10 Sept 2021 · 64 MW · 33 11 Sept 2021 · 1 MW · 1 12 Sept 2021 · 3 MW · 4 13 Sept 2021 · 45 MW · 19 14 Sept 2021 · 37 MW · 32 15 Sept 2021 · 12 MW · 7 18 Sept 2021 · 20 MW · 7 19 Sept 2021 · 12 MW · 3 20 Sept 2021 · 70 MW · 11 21 Sept 2021 · 4,076 MW · 76 22 Sept 2021 · 2,134 MW · 129 23 Sept 2021 · 164 MW · 51 24 Sept 2021 · 931 MW · 101 25 Sept 2021 · 259 MW · 74 26 Sept 2021 · 119 MW · 31 27 Sept 2021 · 51 MW · 18 29 Sept 2021 · 4 MW · 3 30 Sept 2021 · 7 MW · 7 2 Oct 2021 · 3 MW · 2 4 Oct 2021 · 8 MW · 6 5 Oct 2021 · 5 MW · 4
15 Aug 17 Aug 22 Aug 29 Aug 5 Sept 12 Sept 21 Sept 29 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

32°high
67km/h · peak gust
10%lowest humidity

It had gone 15 days without rain (1 mm or more) when it started. Rain came after the fire: 1.3 mm on 6 Oct.

This area had burned before

2% of the perimeter overlaps earlier fires recorded since 2016: 1,423 ha in 2019.

How big is it?

10 km
It burned the equivalent of 58% of the area of London (918 km² against 1,583 km²).

London boundary: geoBoundaries · Office for National Statistics (Open Government Licence v3.0).

This compares size, not location: both shapes are at the same scale, north up, centred on each other.

What happened to each county

  1. El Dorado where it started
    90,912 ha reached on 15 Aug
    20 %
  2. Amador
    448 ha reached on 31 Aug
    0.3 %
  3. Alpine
    352 ha reached on 2 Sept
    0.2 %

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 2020
Built-up area26 ha
Residents≈ 1,600

Inside the perimeter there were about 26 hectares of built-up land and about 1,600 residents (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)
15 Aug 32.4 °C 18 % 34 km/h 0.0 mm High 36
16 Aug 31.0 °C 21 % 46 km/h 0.0 mm Very high 43
17 Aug 25.6 °C 22 % 61 km/h 0.0 mm Very high 46
18 Aug 20.8 °C 31 % 50 km/h 0.0 mm High 34
19 Aug 23.3 °C 23 % 36 km/h 0.0 mm High 32
20 Aug 23.3 °C 30 % 46 km/h 0.0 mm High 33
21 Aug 20.5 °C 36 % 62 km/h 0.0 mm High 35
22 Aug 23.4 °C 31 % 46 km/h 0.0 mm High 30
23 Aug 23.1 °C 29 % 50 km/h 0.0 mm High 32
24 Aug 23.4 °C 28 % 48 km/h 0.0 mm High 32
25 Aug 23.9 °C 21 % 51 km/h 0.0 mm High 36
26 Aug 27.0 °C 14 % 40 km/h 0.0 mm Very high 39
27 Aug 28.6 °C 13 % 44 km/h 0.0 mm Very high 44
28 Aug 30.0 °C 14 % 41 km/h 0.0 mm Very high 43
29 Aug 29.6 °C 13 % 49 km/h 0.0 mm Very high 47
30 Aug 29.4 °C 14 % 53 km/h 0.0 mm Very high 49
31 Aug 27.3 °C 11 % 55 km/h 0.0 mm Very high 50
1 Sept 23.8 °C 16 % 51 km/h 0.0 mm Very high 47
2 Sept 23.1 °C 19 % 45 km/h 0.0 mm Very high 42
3 Sept 25.3 °C 19 % 42 km/h 0.0 mm Very high 41
4 Sept 28.2 °C 16 % 40 km/h 0.0 mm Very high 41
5 Sept 30.0 °C 10 % 41 km/h 0.0 mm Very high 46
6 Sept 31.0 °C 11 % 44 km/h 0.0 mm Very high 49
7 Sept 31.5 °C 17 % 46 km/h 0.0 mm Very high 49
8 Sept 31.3 °C 15 % 49 km/h 0.0 mm Extreme 50
9 Sept 28.6 °C 17 % 53 km/h 0.3 mm Extreme 51
10 Sept 22.0 °C 46 % 67 km/h 5.2 mm Low 7
11 Sept 24.5 °C 34 % 45 km/h 0.0 mm Moderate 16
12 Sept 25.6 °C 21 % 46 km/h 0.0 mm High 30
13 Sept 25.7 °C 15 % 44 km/h 0.0 mm High 36
14 Sept 27.6 °C 20 % 42 km/h 0.0 mm High 36
15 Sept 24.8 °C 25 % 46 km/h 0.0 mm High 38
16 Sept 23.2 °C 25 % 42 km/h 0.0 mm High 35
17 Sept 22.5 °C 29 % 47 km/h 0.0 mm High 34
18 Sept 19.0 °C 30 % 67 km/h 0.0 mm High 38
19 Sept 18.2 °C 33 % 46 km/h 4.2 mm Low 6
20 Sept 25.1 °C 18 % 45 km/h 0.0 mm High 24
21 Sept 25.2 °C 18 % 45 km/h 0.0 mm High 32
22 Sept 23.4 °C 26 % 54 km/h 0.0 mm High 35
23 Sept 26.5 °C 17 % 41 km/h 0.0 mm High 36
24 Sept 26.7 °C 19 % 42 km/h 0.0 mm High 37
25 Sept 23.8 °C 23 % 45 km/h 0.0 mm High 36
26 Sept 22.4 °C 22 % 52 km/h 0.0 mm Very high 38
27 Sept 19.9 °C 19 % 59 km/h 0.0 mm Very high 41
28 Sept 16.6 °C 25 % 46 km/h 3.5 mm Low 7
29 Sept 20.0 °C 14 % 40 km/h 0.0 mm Moderate 21
30 Sept 23.1 °C 13 % 42 km/h 0.0 mm High 34
1 Oct 22.1 °C 18 % 37 km/h 0.0 mm High 31
2 Oct 23.9 °C 16 % 37 km/h 0.0 mm High 32
3 Oct 22.7 °C 18 % 41 km/h 0.0 mm High 34
4 Oct 21.7 °C 18 % 45 km/h 0.0 mm High 36
5 Oct 19.2 °C 28 % 49 km/h 0.0 mm High 33
6 Oct after 14.1 °C 50 % 66 km/h 1.3 mm Moderate 12

Before and after, from space

Drag the line to compare the same ground before the fire and after it.

Before · 8 Aug 2021
After · 12 Oct 2021

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 · 20,371Every 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 timeSatelliteFRP (MW)LatLon

Other fires nearby

All fires in United States ›

Frequently asked questions

How long did the Caldor Fire last?
The official perimeter only gives the start date (15 August 2021). The end comes from the heat detections inside the perimeter: it burned until 5 October 2021 (52 days from 15 August 2021), 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 91,758 hectares (917.6 km²). Other tallies, such as daily incident reports, may give slightly different figures.
Which counties burned?
The fire entered 3 counties: El Dorado (90,912 ha, 20 %); Amador (448 ha, 0.3 %); Alpine (352 ha, 0.2 %).
What was the weather like?
During the fire the temperature reached 32.4 °C, humidity dropped to 10 % and gusts hit 67 km/h. The fire danger index (FWI) reached 51, 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.

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 ›

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

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.

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How we know this
  • Perimeter: MTBS (US Geological Survey and US Forest Service), 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. 20,371 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.

How we build fire pages: methodology ›

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.