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Tennant Fire, June 2021 Siskiyou

Out · last detection 11 Jul 2021, 10:07 UTC

The fire started on 28 June 2021 in Siskiyou, United States, and satellites saw it burning for 14 days. United States agencies (MTBS / NIFC) mapped an official burnt perimeter of 4,748 hectares, spread across a single county.

It is the 136th largest in California since 2016 (of 442 with a page). Number 94 in United States in 2021, of 385.

Compare with…

Suggestions: Biscar · 2026Elk · 2025Siskiyou · 2026Antelope · 2021

Burnt area
4,748ha
official perimeter (MTBS / NIFC)
Duration
≈ 14days
28 Jun 2021 – 11 Jul 2021
Counties hit
1
counties
Started on
28 Jun
2021
Heat detections
710
in a single hotspot: 615 MW
Danger at start
57
Extreme · FWI index
Average daily power
1.5GW
detected power per day, on average

Where it burned

HOTSPOTS BY DAY 28 Jun11 Jul
11 Jul 2021

How it evolved, day by day

29 Jun 2021 · 13,355 MW · 214 30 Jun 2021 · 2,076 MW · 242 1 Jul 2021 · 992 MW · 113 2 Jul 2021 · 111 MW · 27 3 Jul 2021 · 399 MW · 14 4 Jul 2021 · 589 MW · 52 5 Jul 2021 · 641 MW · 21 6 Jul 2021 · 118 MW · 11 7 Jul 2021 · 23 MW · 2 8 Jul 2021 · 1 MW · 2 10 Jul 2021 · 260 MW · 10 11 Jul 2021 · 1 MW · 2
29 Jun 2 Jul 5 Jul 8 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

38°high
53km/h · peak gust
8%lowest humidity

It had gone 3 days 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.

How big is it?

10 km
It burned the equivalent of 3% of the area of London (47 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
    4,764 ha reached on 29 Jun
    0.3 %

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 area0.34 ha
Residents< 20

Inside the perimeter there were about 0.34 hectares of 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)

Started with Extreme FWI: 36 % of the area in United States Very dry air: 40 % of the area in United States

Day High Min. humidity Peak gust Rain Danger (FWI)
28 Jun 37.7 °C 10 % 39 km/h 0.0 mm Extreme 57
29 Jun 36.4 °C 8 % 46 km/h 0.0 mm Extreme 54
30 Jun 34.9 °C 15 % 45 km/h 0.5 mm Very high 49
1 Jul 33.0 °C 15 % 46 km/h 0.0 mm Very high 49
2 Jul 34.2 °C 12 % 42 km/h 0.0 mm Very high 48
3 Jul 34.9 °C 11 % 53 km/h 0.0 mm Very high 49
4 Jul 32.6 °C 17 % 46 km/h 0.2 mm Extreme 55
5 Jul 34.0 °C 14 % 44 km/h 0.0 mm Very high 49
6 Jul 33.9 °C 13 % 48 km/h 0.0 mm Extreme 50
7 Jul 31.5 °C 10 % 48 km/h 0.0 mm Extreme 53
8 Jul 31.6 °C 11 % 50 km/h 0.0 mm Extreme 59
9 Jul 36.1 °C 9 % 45 km/h 0.0 mm Very high 50
10 Jul 36.3 °C 13 % 52 km/h 0.0 mm Extreme 54
11 Jul 36.0 °C 14 % 53 km/h 0.0 mm Very high 50
12 Jul after 34.4 °C 13 % 56 km/h 0.0 mm Extreme 57
13 Jul after 34.3 °C 12 % 52 km/h 0.0 mm Very high 50
14 Jul after 34.4 °C 12 % 50 km/h 0.0 mm Extreme 54
15 Jul after 31.6 °C 17 % 49 km/h 0.2 mm Extreme 53
16 Jul after 28.8 °C 21 % 45 km/h 0.5 mm Extreme 51
17 Jul after 31.4 °C 14 % 48 km/h 0.3 mm Very high 46
18 Jul after 34.3 °C 5 % 40 km/h 0.0 mm Very high 43
19 Jul after 32.3 °C 11 % 46 km/h 0.0 mm Extreme 58
20 Jul after 31.4 °C 12 % 55 km/h 0.0 mm Extreme 52
21 Jul after 27.8 °C 22 % 49 km/h 0.4 mm Very high 45

Its twins: fires that started in the same weather

It started with an FWI of 57.2, a minimum humidity of 10% and 3 days without rain. Fires in the area that started in weather like this since 2016: 19.

FWI at the start 57.2
Minimum humidity 10 %
Days without rain 3
this fire chosen twins rest of the area
Almost identicalSimilar

Outlines of the closest twins

Biscar Fire, July 2026
28,066 ha 4 days FWI 56.1 Min. humidity 13 % 200 km away, in 2026

First rain (1 mm or more) after it ended: none in the following ten days.

See its page Compare with this fire

What happened to them

8 days
median duration
5,645 ha
median area
42 %
went past 10,000 ha
1.9 mm
rain at the end (median; 15 of 19 had it)

It burned an area similar to its twins (4,748 ha against a median of 5,645 ha) and lasted 14 days, against 8 days.

In 4 of 19, 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 1.9 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
53km/h · max. gust

It was considered over on 11 Jul, and not even 1 mm fell in the following ten days: it went out without rain. Twins with rain when they ended: 15 of 19, with a median of 1.9 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.

How we calculate it

Before and after, from space

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

Before · 21 Jun 2021
After · 18 Jul 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 · 710Every 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 Tennant Fire last?
The official perimeter only gives the start date (28 June 2021). The end comes from the heat detections inside the perimeter: it burned until 11 July 2021 (14 days from 28 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 4,748 hectares (47.5 km²). Other tallies, such as daily incident reports, may give slightly different figures.
Which counties burned?
The fire only entered Siskiyou (4,764 ha, 0.3 %).
What was the weather like?
During the fire the temperature reached 37.7 °C, humidity dropped to 8 % and gusts hit 53 km/h. The fire danger index (FWI) reached 59, 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: 19. Their median duration was 8 days and their median area 5,645 ha; 42 % went past 10,000 ha. In 4 of 19, 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 1.9 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

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
What do you think is wrong?

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. 710 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.