Skip to content
worldfires
US · United States · →

Prospect Fire, September 2018 Custer, Valley

Out · last detection 26 Sept 2018, 21:38 UTC

The fire started on 25 September 2018 in Custer, United States, and satellites saw it burning for 1 day. United States agencies (MTBS / NIFC) mapped an official burnt perimeter of 2,807 hectares, spread across 2 counties.

It is the 108th largest in Idaho since 2016 (of 379 with a page). Number 158 in United States in 2018, of 511.

Burnt area
2,807ha
official perimeter (MTBS / NIFC)
Duration
1day
25 Sept 2018 – 25 Sept 2018
Municipalities hit
2
counties
Started on
25 Sept
2018
Heat detections
356
in a single hotspot: 304 MW
Danger at start
18
Moderate · FWI index
Energy released
1.2GW
sum of detected power

Where it burned

HOTSPOTS BY DAY 25 Sept25 Sept

How it evolved, day by day

26

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

The weather it burned in

21°high
70km/h · peak gust
19%lowest humidity

It had gone one day without rain (1 mm or more) when it started. Rain came after the fire: 10.7 mm on 4 Oct.

This area had burned before

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

What happened to each town

  1. Custer where it started
    1,593 ha reached on 28 Sept
    0.1 %
  2. Valley
    1,222 ha reached on 26 Sept
    0.1 %

Burnt area inside each county, from crossing the official perimeter with administrative boundaries. The distance is from the town centre to the nearest fire: staying a kilometre away does not mean it reached the houses.

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 Sept 15.8 °C 22 % 30 km/h 0.0 mm Moderate 18
26 Sept after 18.5 °C 19 % 37 km/h 0.0 mm High 23
27 Sept after 20.6 °C 26 % 46 km/h 0.0 mm High 26
28 Sept after 19.6 °C 24 % 50 km/h 0.0 mm High 28
29 Sept after 19.2 °C 21 % 41 km/h 0.0 mm High 26
30 Sept after 11.8 °C 52 % 52 km/h 5.7 mm Very low 1
1 Oct after 12.6 °C 41 % 57 km/h 0.0 mm Low 6
2 Oct after 11.9 °C 55 % 70 km/h 2.0 mm Low 5
3 Oct after 14.1 °C 25 % 54 km/h 0.8 mm Low 7
4 Oct after 7.3 °C 69 % 36 km/h 10.7 mm Very low 0

Before and after, from space

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

Before · 18 Sept 2018
After · 2 Oct 2018

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 · 356Every 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 Prospect fire last?
It burned between 25 September 2018 and 25 September 2018: 1 day, according to the start date recorded by United States agencies (MTBS / NIFC) and the heat detections seen by satellite.
How much area did it burn?
The official perimeter published by United States agencies (MTBS / NIFC) is 2,807 hectares (28.1 km²). Other tallies, such as daily incident reports, may give slightly different figures.
Which counties burned?
The fire entered 2 counties: Custer (1,593 ha, 0.1 %); Valley (1,222 ha, 0.1 %).
What was the weather like?
During the fire the temperature reached 20.6 °C, humidity dropped to 19 % and gusts hit 70 km/h. The fire danger index (FWI) reached 28, class High.
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

Satellite cross-check

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.

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.