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Palmer Fire, September 2017 Riverside, San Bernardino

Out · last detection 3 Sept 2017, 09:50 UTC

The fire started on 2 September 2017 in Riverside, United States, and satellites saw it burning for 2 days. United States agencies (MTBS / NIFC) mapped an official burnt perimeter of 1,678 hectares, spread across 2 counties.

It is the 229th largest in California since 2016 (of 442 with a page). Number 289 in United States in 2017, of 619.

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Burnt area
1,678ha
official perimeter (MTBS / NIFC)
Duration
≈ 2days
2 Sept 2017 – 3 Sept 2017
Counties hit
2
counties
Started on
2 Sept
2017
Heat detections
15
in a single hotspot: 339 MW
Danger at start
48
Very high · FWI index
Average daily power
826MW
detected power per day, on average

Where it burned

HOTSPOTS BY DAY 2 Sept3 Sept
3 Sept 2017

How it evolved, day by day

2 Sept 2017 · 1,649 MW · 13 3 Sept 2017 · 2 MW · 2
2 Sept 3 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

39°high
48km/h · peak gust
18%lowest humidity

It had gone 29 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 1.1% of the area of London (17 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. Riverside where it started
    1,644 ha reached on 2 Sept
    0.1 %
  2. San Bernardino
    36 ha
    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 area2.2 ha
Residents≈ 50

Inside the perimeter there were about 2.2 hectares of built-up land and about 50 residents (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)
2 Sept 38.8 °C 18 % 43 km/h 0.0 mm Very high 48
3 Sept 32.7 °C 43 % 48 km/h 13.3 mm Very low 4
4 Sept after 32.2 °C 43 % 42 km/h 0.3 mm Moderate 14
5 Sept after 32.1 °C 39 % 32 km/h 0.3 mm Moderate 21
6 Sept after 32.8 °C 39 % 34 km/h 0.0 mm High 23
7 Sept after 32.4 °C 29 % 34 km/h 0.0 mm High 26
8 Sept after 30.5 °C 29 % 34 km/h 0.0 mm High 29
9 Sept after 29.8 °C 37 % 30 km/h 0.5 mm High 26
10 Sept after 35.0 °C 26 % 31 km/h 0.0 mm High 29
11 Sept after 35.1 °C 29 % 40 km/h 0.0 mm High 31
12 Sept after 32.7 °C 33 % 42 km/h 0.0 mm High 34
13 Sept after 30.2 °C 29 % 40 km/h 0.0 mm High 33

Before and after, from space

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

Before · 26 Aug 2017
After · 10 Sept 2017

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 · 15Every 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 Palmer Fire last?
The official perimeter only gives the start date (2 September 2017). The end comes from the heat detections inside the perimeter: it burned until 3 September 2017 (2 days from 2 September 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 1,678 hectares (16.8 km²). Other tallies, such as daily incident reports, may give slightly different figures.
Which counties burned?
The fire entered 2 counties: Riverside (1,644 ha, 0.1 %); San Bernardino (36 ha, 0.0 %).
What was the weather like?
During the fire the temperature reached 38.8 °C, humidity dropped to 18 % and gusts hit 48 km/h. The fire danger index (FWI) reached 48, class Very 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 · 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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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. 15 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.