How long did the Issac Lake Fire last?

The official perimeter only gives the start date (17 August 2017). The end comes from the heat detections inside the perimeter: it burned until 13 September 2017 (28 days from 17 August 2017), 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 943 hectares (9.4 km²). Other tallies, such as daily incident reports, may give slightly different figures.

Which counties burned?

The fire only entered Idaho (949 ha, 0.0 %).

What was the weather like?

During the fire the temperature reached 30.0 °C, humidity dropped to 5 % and gusts hit 54 km/h. The fire danger index (FWI) reached 51, 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 · 2017-08-17 → 2017-09-13

Issac Lake Fire, August 2017 Idaho

Out · last detection 13 Sept 2017, 19:45 UTC

The fire started on 17 August 2017 in Idaho, United States, and satellites saw it burning for 28 days. United States agencies (MTBS / NIFC) mapped an official burnt perimeter of 943 hectares, spread across a single county.

It is the 236th largest in Idaho since 2016 (of 379 with a page). Number 399 in United States in 2017, of 619.

Compare with…

Suggestions: Moose · 2016 Warm Springs · 2022 Moose Creek 1 · 2017 Lone Pine · 2017

Burnt area: 943ha; official perimeter (MTBS / NIFC)
Duration: ≈ 28days; 17 Aug 2017 – 13 Sept 2017
Counties hit: 1; counties
Started on: 17 Aug; 2017
Heat detections: 287; in a single hotspot: 175 MW
Danger at start: 32; High · FWI index
Average daily power: 98MW; detected power per day, on average

HOTSPOTS BY DAY 17 Aug13 Sept

Play back 13 Sept 2017

How it evolved, day by day

21 Aug 27 Aug 30 Aug 3 Sept 6 Sept 9 Sept 12 Sept

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

The weather it burned in

30°high

54km/h · peak gust

5%lowest humidity

It had gone 3 days without rain (1 mm or more) when it started. Rain came after the fire: 3.5 mm on 14 Sept.

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 0.6% of the area of London (9.4 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

Idaho where it started

949 ha reached on 21 Aug

0.0 %

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 2015

Built-up area< 0.1 ha

Residents< 20

Inside the perimeter there was no noticeable built-up land and almost nobody lived there (GHSL 2015, 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)
17 Aug	23.5 °C	21 %	44 km/h	0.0 mm	High 32
18 Aug	25.6 °C	13 %	50 km/h	0.0 mm	High 38
19 Aug	20.5 °C	22 %	53 km/h	0.0 mm	High 36
20 Aug	20.6 °C	18 %	38 km/h	0.0 mm	High 33
21 Aug	25.2 °C	15 %	25 km/h	0.0 mm	High 32
22 Aug	27.6 °C	11 %	44 km/h	0.0 mm	Very high 41
23 Aug	26.4 °C	15 %	41 km/h	0.0 mm	Very high 39
24 Aug	22.4 °C	26 %	52 km/h	0.4 mm	High 37
25 Aug	23.1 °C	18 %	48 km/h	0.0 mm	High 35
26 Aug	26.1 °C	9 %	41 km/h	0.0 mm	Very high 41
27 Aug	28.8 °C	5 %	41 km/h	0.0 mm	Very high 48
28 Aug	27.0 °C	14 %	52 km/h	0.0 mm	Very high 46
29 Aug	30.0 °C	5 %	31 km/h	0.1 mm	Very high 44
30 Aug	26.1 °C	12 %	53 km/h	0.0 mm	Extreme 51
31 Aug	23.6 °C	17 %	54 km/h	0.0 mm	Very high 46
1 Sept	26.2 °C	15 %	42 km/h	0.0 mm	Very high 42
2 Sept	29.9 °C	8 %	53 km/h	0.0 mm	Very high 50
3 Sept	29.9 °C	7 %	53 km/h	0.0 mm	Extreme 51
4 Sept	26.5 °C	13 %	35 km/h	0.0 mm	Very high 45
5 Sept	26.5 °C	10 %	30 km/h	0.0 mm	Very high 43
6 Sept	26.9 °C	11 %	34 km/h	0.0 mm	Very high 43
7 Sept	29.2 °C	9 %	22 km/h	0.0 mm	Very high 42
8 Sept	25.8 °C	18 %	42 km/h	0.3 mm	Very high 42
9 Sept	24.7 °C	28 %	52 km/h	0.4 mm	Very high 40
10 Sept	21.4 °C	31 %	49 km/h	0.0 mm	High 33
11 Sept	27.0 °C	7 %	35 km/h	0.0 mm	Very high 42
12 Sept	25.1 °C	18 %	53 km/h	0.0 mm	Very high 45
13 Sept	19.6 °C	28 %	53 km/h	0.0 mm	High 37
14 Sept after	13.9 °C	25 %	42 km/h	3.5 mm	Low 6

Before and after, from space

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

↔

Before · 10 Aug 2017

After · 20 Sept 2017

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 · 287Every 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 Issac Lake Fire last?: The official perimeter only gives the start date (17 August 2017). The end comes from the heat detections inside the perimeter: it burned until 13 September 2017 (28 days from 17 August 2017), 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 943 hectares (9.4 km²). Other tallies, such as daily incident reports, may give slightly different figures.
Which counties burned?: The fire only entered Idaho (949 ha, 0.0 %).
What was the weather like?: During the fire the temperature reached 30.0 °C, humidity dropped to 5 % and gusts hit 54 km/h. The fire danger index (FWI) reached 51, 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.

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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. 287 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 2015, 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