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Box Fire, September 2023 Sevier, Sanpete

Out · last measured on 19 Sept 2023

The fire started on 19 September 2023 in Sevier, United States, and satellites saw it burning for 1 day. United States agencies (MTBS / NIFC) mapped an official burnt perimeter of 777 hectares, spread across 2 counties.

It is the 122th largest in Utah since 2016 (of 165 with a page). Number 191 in United States in 2023, of 305.

Burnt area
777ha
official perimeter (MTBS / NIFC)
Duration
1day
19 Sept 2023 – 19 Sept 2023
Municipalities hit
2
counties
Started on
19 Sept
2023
Heat detections
28
in a single hotspot: 32 MW
Danger at start
20
Moderate · FWI index

Where it burned

HOTSPOTS BY DAY 19 Sept19 Sept

The weather it burned in

22°high
55km/h · peak gust
14%lowest humidity

It had gone 6 days without rain (1 mm or more) when it started. Rain came after the fire: 3.7 mm on 1 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. Sevier where it started
    771 ha reached on 22 Sept
    0.2 %
  2. Sanpete
    10 ha reached on 26 Sept
    0.0 %

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)
19 Sept 20.0 °C 20 % 35 km/h 0.2 mm Moderate 20
20 Sept after 20.0 °C 18 % 45 km/h 0.3 mm High 28
21 Sept after 16.3 °C 20 % 48 km/h 0.9 mm Moderate 21
22 Sept after 17.8 °C 20 % 55 km/h 0.0 mm High 26
23 Sept after 17.6 °C 18 % 29 km/h 0.0 mm Moderate 19
24 Sept after 19.7 °C 15 % 26 km/h 0.0 mm High 23
25 Sept after 20.9 °C 14 % 32 km/h 0.0 mm High 27
26 Sept after 21.9 °C 16 % 26 km/h 0.0 mm High 25
27 Sept after 23.1 °C 13 % 32 km/h 0.0 mm High 28
28 Sept after 22.3 °C 10 % 37 km/h 0.0 mm High 29
29 Sept after 22.3 °C 12 % 48 km/h 0.0 mm Very high 39
30 Sept after 19.0 °C 10 % 65 km/h 0.1 mm Very high 45
1 Oct after 11.8 °C 35 % 58 km/h 3.7 mm Very low 5

Before and after, from space

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

Before · 12 Sept 2023
After · 26 Sept 2023

If the day is cloudy, change the date: each satellite passes once a day. In false colour the burnt ground looks brown or red.

The smoke

CAMS · Copernicus

On 19 September 2023 the air beside the fire reached 7 µg/m³ of PM2.5, but no daily average passed the WHO guideline (15).

PM2.5 peak7 µg/m³
Days over the guideline0 days
PM1011 µg/m³
Optical depth0.17
171819202122
Good Fair Moderate Poor Very poor Extremely poor

Particles from the Copernicus CAMS model at the centre of the perimeter; these are not measurements in each town. The pale bar is the worst hour, the solid one the daily average.

Open-Meteo.com (CC BY 4.0) · Copernicus Atmosphere Monitoring Service (CAMS)

Detections table · 28Every 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 Box fire last?
It burned between 19 September 2023 and 19 September 2023: 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 777 hectares (7.8 km²). Other tallies, such as daily incident reports, may give slightly different figures.
Which counties burned?
The fire entered 2 counties: Sevier (771 ha, 0.2 %); Sanpete (10 ha, 0.0 %).
What was the weather like?
During the fire the temperature reached 21.9 °C, humidity dropped to 14 % and gusts hit 55 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.

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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.

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.