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Bighorn Fire, June 2020 Pima, Pinal

Out · last detection 20 Jul 2020, 09:44 UTC

The fire started on 6 June 2020 in Pima, United States, and satellites saw it burning for 45 days. United States agencies (MTBS / NIFC) mapped an official burnt perimeter of 51,005 hectares, spread across 2 counties.

It is the 5th largest in Arizona since 2016 (of 380 with a page). Number 22 in United States in 2020, of 441.

Compare with…

Suggestions: Burro · 2017Chimney · 2023Cody · 2025Gor - Flood · 2024

Burnt area
51,005ha
official perimeter (MTBS / NIFC)
Duration
≈ 45days
6 Jun 2020 – 20 Jul 2020
Counties hit
2
counties
Started on
6 Jun
2020
Heat detections
4,392
in a single hotspot: 674 MW
Danger at start
42
Very high · FWI index
Average daily power
1.8GW
detected power per day, on average

Where it burned

HOTSPOTS BY DAY 6 Jun20 Jul
20 Jul 2020

How it evolved, day by day

6 Jun 2020 · 107 MW · 9 7 Jun 2020 · 957 MW · 85 8 Jun 2020 · 94 MW · 8 9 Jun 2020 · 159 MW · 26 10 Jun 2020 · 235 MW · 14 11 Jun 2020 · 661 MW · 67 12 Jun 2020 · 1,128 MW · 70 13 Jun 2020 · 820 MW · 47 14 Jun 2020 · 310 MW · 57 15 Jun 2020 · 265 MW · 49 16 Jun 2020 · 417 MW · 44 17 Jun 2020 · 18,348 MW · 288 18 Jun 2020 · 5,608 MW · 442 19 Jun 2020 · 2,367 MW · 215 20 Jun 2020 · 3,344 MW · 336 21 Jun 2020 · 2,773 MW · 314 22 Jun 2020 · 5,590 MW · 542 23 Jun 2020 · 7,088 MW · 492 24 Jun 2020 · 1,691 MW · 232 25 Jun 2020 · 4,168 MW · 176 26 Jun 2020 · 1,423 MW · 153 27 Jun 2020 · 4,351 MW · 196 28 Jun 2020 · 1,803 MW · 141 29 Jun 2020 · 2,671 MW · 124 30 Jun 2020 · 1,152 MW · 134 1 Jul 2020 · 399 MW · 55 2 Jul 2020 · 18 MW · 13 3 Jul 2020 · 82 MW · 20 4 Jul 2020 · 65 MW · 5 5 Jul 2020 · 15 MW · 10 6 Jul 2020 · 14 MW · 7 7 Jul 2020 · 18 MW · 2 8 Jul 2020 · 36 MW · 4 9 Jul 2020 · 1 MW · 1 12 Jul 2020 · 1 MW · 2 14 Jul 2020 · 20 MW · 2 16 Jul 2020 · 156 MW · 6 17 Jul 2020 · 6 MW · 3 20 Jul 2020 · 3 MW · 1
6 Jun 12 Jun 17 Jun 18 Jun 24 Jun 30 Jun 6 Jul 16 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

33°high
77km/h · peak gust
4%lowest humidity

It had gone 4 days without rain (1 mm or more) when it started. Rain came after the fire: 15.3 mm on 23 Jul.

This area had burned before

14% of the perimeter overlaps earlier fires recorded since 2016: 6,978 ha in 2017.

How big is it?

10 km
It burned the equivalent of 32% of the area of London (510 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. Pima where it started
    44,766 ha reached on 6 Jun
    1.9 %
  2. Pinal
    6,568 ha reached on 20 Jun
    0.5 %

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 area9.6 ha
Residents≈ 50

Inside the perimeter there were about 9.6 hectares of built-up land and about 50 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)
6 Jun 23.5 °C 11 % 48 km/h 0.3 mm Very high 42
7 Jun 23.5 °C 16 % 63 km/h 0.0 mm Very high 50
8 Jun 20.7 °C 7 % 63 km/h 0.0 mm Extreme 54
9 Jun 23.5 °C 4 % 33 km/h 0.0 mm Very high 45
10 Jun 28.4 °C 6 % 33 km/h 0.0 mm Very high 47
11 Jun 29.9 °C 6 % 41 km/h 0.0 mm Extreme 51
12 Jun 30.3 °C 9 % 45 km/h 0.0 mm Extreme 55
13 Jun 29.0 °C 8 % 64 km/h 0.0 mm Extreme 64
14 Jun 28.0 °C 8 % 62 km/h 0.0 mm Extreme 60
15 Jun 27.4 °C 11 % 49 km/h 0.0 mm Extreme 51
16 Jun 28.7 °C 8 % 64 km/h 0.0 mm Extreme 61
17 Jun 27.7 °C 7 % 64 km/h 0.0 mm Extreme 62
18 Jun 27.0 °C 5 % 50 km/h 0.0 mm Extreme 56
19 Jun 27.1 °C 4 % 48 km/h 0.0 mm Extreme 54
20 Jun 28.0 °C 9 % 40 km/h 0.0 mm Extreme 52
21 Jun 29.2 °C 8 % 42 km/h 0.0 mm Extreme 52
22 Jun 29.2 °C 7 % 43 km/h 0.0 mm Extreme 54
23 Jun 29.3 °C 9 % 45 km/h 0.0 mm Extreme 55
24 Jun 31.3 °C 7 % 46 km/h 0.0 mm Extreme 56
25 Jun 31.1 °C 6 % 50 km/h 0.0 mm Extreme 61
26 Jun 30.3 °C 7 % 52 km/h 0.0 mm Extreme 58
27 Jun 28.9 °C 11 % 68 km/h 0.0 mm Extreme 61
28 Jun 26.1 °C 13 % 59 km/h 0.0 mm Extreme 57
29 Jun 26.3 °C 8 % 77 km/h 0.0 mm Extreme 66
30 Jun 25.8 °C 11 % 64 km/h 0.0 mm Extreme 59
1 Jul 26.6 °C 16 % 44 km/h 0.0 mm Very high 48
2 Jul 23.5 °C 29 % 34 km/h 0.4 mm High 36
3 Jul 27.5 °C 22 % 40 km/h 0.0 mm High 37
4 Jul 29.5 °C 18 % 46 km/h 0.0 mm Very high 45
5 Jul 30.4 °C 12 % 44 km/h 0.0 mm Very high 48
6 Jul 30.7 °C 9 % 50 km/h 0.0 mm Extreme 55
7 Jul 30.7 °C 11 % 45 km/h 0.0 mm Extreme 53
8 Jul 30.4 °C 16 % 42 km/h 0.0 mm Extreme 50
9 Jul 30.4 °C 15 % 44 km/h 0.0 mm Extreme 50
10 Jul 31.4 °C 17 % 48 km/h 0.0 mm Extreme 53
11 Jul 31.8 °C 17 % 36 km/h 0.0 mm Extreme 53
12 Jul 32.9 °C 13 % 48 km/h 0.2 mm Very high 49
13 Jul 30.1 °C 18 % 49 km/h 0.2 mm Very high 50
14 Jul 30.0 °C 16 % 49 km/h 0.0 mm Very high 48
15 Jul 28.5 °C 17 % 36 km/h 0.0 mm Very high 48
16 Jul 28.8 °C 15 % 29 km/h 0.0 mm Very high 46
17 Jul 28.2 °C 20 % 34 km/h 0.0 mm Very high 42
18 Jul 29.2 °C 19 % 36 km/h 0.0 mm Very high 45
19 Jul 27.8 °C 17 % 50 km/h 0.0 mm Very high 49
20 Jul 26.7 °C 16 % 49 km/h 0.0 mm Extreme 52
21 Jul after 26.6 °C 15 % 41 km/h 0.0 mm Extreme 51
22 Jul after 25.8 °C 24 % 31 km/h 0.9 mm High 25
23 Jul after 19.2 °C 55 % 24 km/h 15.3 mm Very low 0

Before and after, from space

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

Before · 30 May 2020
After · 27 Jul 2020

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 · 4,392Every 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 Bighorn Fire last?
The official perimeter only gives the start date (6 June 2020). The end comes from the heat detections inside the perimeter: it burned until 20 July 2020 (45 days from 6 June 2020), 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 51,005 hectares (510.0 km²). Other tallies, such as daily incident reports, may give slightly different figures.
Which counties burned?
The fire entered 2 counties: Pima (44,766 ha, 1.9 %); Pinal (6,568 ha, 0.5 %).
What was the weather like?
During the fire the temperature reached 32.9 °C, humidity dropped to 4 % and gusts hit 77 km/h. The fire danger index (FWI) reached 66, 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. 4,392 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.