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Lava Fire, June 2021 Siskiyou

Out · last detection 5 Aug 2021, 10:39 UTC

The fire started on 25 June 2021 in Siskiyou, United States, and satellites saw it burning for 42 days. United States agencies (MTBS / NIFC) mapped an official burnt perimeter of 10,628 hectares, spread across a single county.

It is the 91th largest in California since 2016 (of 442 with a page). Number 51 in United States in 2021, of 385.

Compare with…

Suggestions: Mill · 2022Siskiyou · 2026Mountain · 2022Tennant · 2021

Burnt area
10,628ha
official perimeter (MTBS / NIFC)
Duration
≈ 42days
25 Jun 2021 – 5 Aug 2021
Counties hit
1
counties
Started on
25 Jun
2021
Heat detections
1,551
in a single hotspot: 452 MW
Danger at start
30
High · FWI index
Average daily power
1.8GW
detected power per day, on average

Where it burned

HOTSPOTS BY DAY 25 Jun5 Aug
5 Aug 2021

How it evolved, day by day

26 Jun 2021 · 292 MW · 5 27 Jun 2021 · 1,177 MW · 40 28 Jun 2021 · 31,578 MW · 313 29 Jun 2021 · 13,613 MW · 436 30 Jun 2021 · 4,641 MW · 223 1 Jul 2021 · 2,916 MW · 143 2 Jul 2021 · 339 MW · 93 3 Jul 2021 · 155 MW · 29 4 Jul 2021 · 232 MW · 32 5 Jul 2021 · 31 MW · 17 6 Jul 2021 · 98 MW · 26 7 Jul 2021 · 60 MW · 15 8 Jul 2021 · 62 MW · 25 9 Jul 2021 · 811 MW · 41 10 Jul 2021 · 73 MW · 23 11 Jul 2021 · 41 MW · 21 12 Jul 2021 · 54 MW · 7 13 Jul 2021 · 26 MW · 11 14 Jul 2021 · 209 MW · 15 15 Jul 2021 · 28 MW · 10 16 Jul 2021 · 7 MW · 6 17 Jul 2021 · 7 MW · 2 18 Jul 2021 · 4 MW · 1 19 Jul 2021 · 2 MW · 2 20 Jul 2021 · 8 MW · 2 21 Jul 2021 · 2 MW · 1 22 Jul 2021 · 1 MW · 1 24 Jul 2021 · 8 MW · 4 1 Aug 2021 · 6 MW · 1 2 Aug 2021 · 10 MW · 3 4 Aug 2021 · 3 MW · 1 5 Aug 2021 · 2 MW · 2
26 Jun 28 Jun 1 Jul 6 Jul 11 Jul 16 Jul 21 Jul 4 Aug

Fire radiative power detected each day, in megawatts, and number of hotspots. The magenta bar marks the peak day.

The weather it burned in

37°high
55km/h · peak gust
6%lowest humidity

It had gone 0 days without rain (1 mm or more) when it started. Rain came after the fire: 2.2 mm on 13 Aug.

This area had burned before

No earlier perimeters overlap this fire since 2016, when the satellite record begins.

How big is it?

10 km
It burned the equivalent of 6.7% of the area of London (106 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. Siskiyou where it started
    10,648 ha reached on 26 Jun
    0.6 %

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 area1.7 ha
Residents≈ 30

Inside the perimeter there were about 1.7 hectares of built-up land and about 30 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)
25 Jun 30.1 °C 18 % 46 km/h 0.0 mm High 30
26 Jun 32.8 °C 16 % 39 km/h 0.0 mm High 35
27 Jun 36.0 °C 18 % 33 km/h 0.0 mm High 34
28 Jun 35.2 °C 15 % 55 km/h 0.0 mm Very high 46
29 Jun 34.8 °C 9 % 49 km/h 0.0 mm Very high 47
30 Jun 34.0 °C 16 % 41 km/h 0.0 mm Very high 44
1 Jul 32.3 °C 16 % 40 km/h 0.0 mm Very high 45
2 Jul 33.3 °C 13 % 37 km/h 0.0 mm Very high 44
3 Jul 34.1 °C 13 % 39 km/h 0.0 mm Very high 44
4 Jul 32.0 °C 19 % 39 km/h 0.0 mm Very high 43
5 Jul 33.5 °C 16 % 33 km/h 0.0 mm Very high 41
6 Jul 33.1 °C 15 % 44 km/h 0.0 mm Very high 46
7 Jul 31.9 °C 12 % 42 km/h 0.0 mm Very high 44
8 Jul 32.6 °C 11 % 41 km/h 0.0 mm Very high 45
9 Jul 35.9 °C 9 % 38 km/h 0.0 mm Very high 48
10 Jul 36.8 °C 13 % 44 km/h 0.0 mm Very high 49
11 Jul 36.2 °C 16 % 39 km/h 0.0 mm Very high 48
12 Jul 35.2 °C 14 % 48 km/h 0.0 mm Extreme 50
13 Jul 34.4 °C 13 % 40 km/h 0.0 mm Very high 47
14 Jul 33.7 °C 15 % 37 km/h 0.0 mm Very high 47
15 Jul 30.9 °C 17 % 40 km/h 0.0 mm Very high 45
16 Jul 29.3 °C 22 % 36 km/h 0.0 mm Very high 40
17 Jul 31.4 °C 13 % 36 km/h 0.0 mm Very high 41
18 Jul 33.7 °C 6 % 42 km/h 0.0 mm Extreme 51
19 Jul 31.5 °C 12 % 49 km/h 0.0 mm Extreme 53
20 Jul 31.1 °C 12 % 46 km/h 0.0 mm Extreme 52
21 Jul 29.5 °C 19 % 45 km/h 0.2 mm Very high 45
22 Jul 30.9 °C 13 % 40 km/h 0.0 mm Very high 44
23 Jul 32.7 °C 11 % 31 km/h 0.0 mm Very high 43
24 Jul 32.8 °C 15 % 34 km/h 0.0 mm Very high 43
25 Jul 33.7 °C 18 % 30 km/h 0.0 mm Very high 43
26 Jul 31.8 °C 22 % 38 km/h 0.0 mm Very high 46
27 Jul 22.7 °C 42 % 38 km/h 2.3 mm Low 8
28 Jul 31.5 °C 15 % 39 km/h 0.1 mm High 32
29 Jul 33.3 °C 17 % 39 km/h 0.3 mm High 38
30 Jul 29.9 °C 25 % 34 km/h 2.1 mm Moderate 18
31 Jul 30.5 °C 19 % 34 km/h 0.0 mm High 32
1 Aug 30.7 °C 15 % 43 km/h 0.0 mm Very high 40
2 Aug 30.3 °C 9 % 54 km/h 0.0 mm Very high 49
3 Aug 31.9 °C 9 % 34 km/h 0.0 mm Very high 43
4 Aug 31.2 °C 9 % 45 km/h 0.0 mm Very high 49
5 Aug 23.3 °C 21 % 47 km/h 2.7 mm Moderate 12
6 Aug after 28.0 °C 14 % 37 km/h 0.0 mm High 31
7 Aug after 30.3 °C 21 % 40 km/h 0.0 mm High 33
8 Aug after 28.8 °C 27 % 41 km/h 0.0 mm High 34
9 Aug after 30.8 °C 19 % 27 km/h 0.0 mm High 33
10 Aug after 33.1 °C 15 % 30 km/h 0.0 mm High 37
11 Aug after 34.3 °C 14 % 41 km/h 0.0 mm Very high 45
12 Aug after 33.7 °C 17 % 33 km/h 0.1 mm Very high 41
13 Aug after 31.9 °C 25 % 35 km/h 2.2 mm Moderate 18

Before and after, from space

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

Before · 18 Jun 2021
After · 12 Aug 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 · 1,551Every 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 Lava Fire last?
The official perimeter only gives the start date (25 June 2021). The end comes from the heat detections inside the perimeter: it burned until 5 August 2021 (42 days from 25 June 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 10,628 hectares (106.3 km²). Other tallies, such as daily incident reports, may give slightly different figures.
Which counties burned?
The fire only entered Siskiyou (10,648 ha, 0.6 %).
What was the weather like?
During the fire the temperature reached 36.8 °C, humidity dropped to 6 % and gusts hit 55 km/h. The fire danger index (FWI) reached 53, 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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We will only use your email to reply about this report. Privacy. This is not an emergency service: if there is a fire now, call 911.

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. 1,551 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.