How long did the Dollar Ridge Fire last?

The official perimeter only gives the start date (1 July 2018). The end comes from the heat detections inside the perimeter: it burned until 20 August 2018 (51 days from 1 July 2018), 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 28,232 hectares (282.3 km²). Other tallies, such as daily incident reports, may give slightly different figures.

Which counties burned?

The fire entered 2 counties: Wasatch (16,885 ha, 5.4 %); Duchesne (11,338 ha, 1.3 %).

What was the weather like?

During the fire the temperature reached 31.6 °C, humidity dropped to 7 % and gusts hit 65 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.

US · United States · 2018-07-01 → 2018-08-20

Dollar Ridge Fire, July 2018 Wasatch, Duchesne

Out · last detection 20 Aug 2018, 10:07 UTC

The fire started on 1 July 2018 in Duchesne, United States, and satellites saw it burning for 51 days. United States agencies (MTBS / NIFC) mapped an official burnt perimeter of 28,232 hectares, spread across 2 counties.

It is the 10th largest in Utah since 2016 (of 165 with a page). Number 20 in United States in 2018, of 511.

Compare with…

Suggestions: Tank Hollow · 2017 Sheep Creek · 2016 Jocks Canyon · 2016 Sawmill · 2016

Burnt area: 28,232ha; official perimeter (MTBS / NIFC)
Duration: ≈ 51days; 1 Jul 2018 – 20 Aug 2018
Counties hit: 2; counties
Started on: 1 Jul; 2018
Heat detections: 2,743; in a single hotspot: 997 MW
Danger at start: 46; Very high · FWI index
Average daily power: 2.7GW; detected power per day, on average

HOTSPOTS BY DAY 1 Jul20 Aug

Play back 20 Aug 2018

How it evolved, day by day

1 Jul 4 Jul 6 Jul 21 Jul 3 Aug 9 Aug 14 Aug 20 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

32°high

65km/h · peak gust

7%lowest humidity

It had gone 13 days without rain (1 mm or more) when it started. Rain came after the fire: 13.0 mm on 21 Aug.

This area had burned before

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

How big is it?

It burned the equivalent of 18% of the area of London (282 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

Wasatch

16,885 ha reached on 1 Jul

5.4 %
Duchesne where it started

11,338 ha reached on 2 Jul

1.3 %

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 area1.2 ha

Residents< 20

Inside the perimeter there were about 1.2 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)

Day	High	Min. humidity	Peak gust	Rain	Danger (FWI)
1 Jul	26.1 °C	13 %	50 km/h	0.0 mm	Very high 46
2 Jul	29.4 °C	9 %	59 km/h	0.0 mm	Extreme 54
3 Jul	29.3 °C	7 %	65 km/h	0.0 mm	Extreme 59
4 Jul	30.3 °C	8 %	43 km/h	0.0 mm	Very high 48
5 Jul	30.4 °C	10 %	40 km/h	0.7 mm	Very high 44
6 Jul	31.4 °C	19 %	33 km/h	0.0 mm	Very high 41
7 Jul	31.1 °C	16 %	42 km/h	0.1 mm	Very high 45
8 Jul	30.8 °C	20 %	31 km/h	2.3 mm	Moderate 20
9 Jul	30.7 °C	23 %	34 km/h	1.0 mm	High 25
10 Jul	30.4 °C	21 %	36 km/h	0.5 mm	High 34
11 Jul	28.2 °C	28 %	34 km/h	3.9 mm	Low 8
12 Jul	27.1 °C	37 %	30 km/h	2.2 mm	Low 7
13 Jul	29.0 °C	25 %	22 km/h	0.0 mm	Moderate 20
14 Jul	26.1 °C	36 %	44 km/h	4.4 mm	Low 5
15 Jul	28.5 °C	23 %	27 km/h	0.0 mm	Moderate 17
16 Jul	29.5 °C	19 %	27 km/h	1.3 mm	Moderate 19
17 Jul	29.3 °C	20 %	52 km/h	0.1 mm	High 34
18 Jul	30.4 °C	15 %	50 km/h	0.0 mm	Very high 40
19 Jul	30.9 °C	15 %	52 km/h	0.0 mm	Very high 41
20 Jul	27.9 °C	21 %	36 km/h	0.3 mm	High 36
21 Jul	30.8 °C	20 %	43 km/h	0.3 mm	Very high 44
22 Jul	27.1 °C	32 %	47 km/h	0.8 mm	High 24
23 Jul	29.8 °C	22 %	34 km/h	0.3 mm	High 30
24 Jul	30.8 °C	16 %	41 km/h	0.0 mm	Very high 38
25 Jul	28.6 °C	24 %	51 km/h	1.4 mm	High 27
26 Jul	29.6 °C	13 %	49 km/h	0.0 mm	Very high 42
27 Jul	29.2 °C	15 %	48 km/h	1.1 mm	High 35
28 Jul	28.7 °C	16 %	52 km/h	0.9 mm	Very high 39
29 Jul	28.7 °C	12 %	58 km/h	0.0 mm	Extreme 50
30 Jul	29.6 °C	10 %	44 km/h	0.0 mm	Very high 47
31 Jul	30.5 °C	12 %	41 km/h	0.0 mm	Very high 48
1 Aug	27.9 °C	22 %	43 km/h	0.6 mm	High 36
2 Aug	25.9 °C	24 %	34 km/h	5.5 mm	Low 7
3 Aug	27.0 °C	22 %	52 km/h	0.2 mm	High 26
4 Aug	27.7 °C	17 %	56 km/h	0.8 mm	High 37
5 Aug	27.6 °C	14 %	63 km/h	0.4 mm	Very high 47
6 Aug	28.3 °C	9 %	51 km/h	0.0 mm	Very high 48
7 Aug	28.7 °C	10 %	52 km/h	0.0 mm	Very high 50
8 Aug	29.7 °C	9 %	47 km/h	0.0 mm	Extreme 50
9 Aug	31.6 °C	8 %	26 km/h	0.0 mm	Very high 42
10 Aug	31.6 °C	10 %	38 km/h	0.0 mm	Very high 49
11 Aug	31.3 °C	10 %	22 km/h	0.0 mm	Very high 43
12 Aug	30.6 °C	14 %	35 km/h	0.3 mm	Very high 45
13 Aug	28.2 °C	17 %	36 km/h	0.0 mm	Very high 43
14 Aug	28.1 °C	17 %	45 km/h	0.4 mm	Very high 45
15 Aug	26.4 °C	15 %	37 km/h	1.3 mm	High 27
16 Aug	28.4 °C	24 %	37 km/h	0.2 mm	High 31
17 Aug	27.5 °C	19 %	34 km/h	0.3 mm	High 38
18 Aug	24.4 °C	22 %	59 km/h	1.4 mm	High 30
19 Aug	27.5 °C	14 %	31 km/h	0.0 mm	High 33
20 Aug	26.7 °C	19 %	52 km/h	1.0 mm	High 35
21 Aug after	22.8 °C	39 %	41 km/h	13.0 mm	Very low 3

Before and after, from space

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

↔

Before · 24 Jun 2018

After · 27 Aug 2018

Before After

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 · 2,743Every 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

All fires in United States ›

Frequently asked questions

How long did the Dollar Ridge Fire last?: The official perimeter only gives the start date (1 July 2018). The end comes from the heat detections inside the perimeter: it burned until 20 August 2018 (51 days from 1 July 2018), 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 28,232 hectares (282.3 km²). Other tallies, such as daily incident reports, may give slightly different figures.
Which counties burned?: The fire entered 2 counties: Wasatch (16,885 ha, 5.4 %); Duchesne (11,338 ha, 1.3 %).
What was the weather like?: During the fire the temperature reached 31.6 °C, humidity dropped to 7 % and gusts hit 65 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.

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

NASA FIRMS ↗
NIFC · Fire maps ↗

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

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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. 2,743 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.

Where it burned