Border Fire, September 2023 Grand, Mesa
The fire started on 21 September 2023 in Grand, United States, and satellites saw it burning for 1 day. United States agencies (MTBS / NIFC) mapped an official burnt perimeter of 503 hectares, spread across 2 counties.
It is the 162th largest in Utah since 2016 (of 165 with a page). Number 264 in United States in 2023, of 305.
The power measured by the satellite is low (7.3 MW in the strongest hotspot), more typical of grass or stubble burning, or a slow surface fire, than of a large crown fire.
- Burnt area
- 503ha
- official perimeter (MTBS / NIFC)
- Duration
- 1day
- 21 Sept 2023 – 21 Sept 2023
- Municipalities hit
- 2
- counties
- Started on
- 21 Sept
- 2023
- Heat detections
- 18
- in a single hotspot: 7 MW
- Danger at start
- 57
- Extreme · FWI index
- Energy released
- 74MW
- sum of detected power
Where it burned
How it evolved, day by day
Fire radiative power detected each day, in megawatts, and number of hotspots. The magenta bar marks the peak day.
The weather it burned in
It had gone 26 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.
What happened to each town
-
Grand where it started316 ha reached on 21 Sept0.0 %
-
188 ha reached on 21 Sept0.0 %
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) |
|---|---|---|---|---|---|
| 21 Sept | 28.2 °C | 10 % | 54 km/h | 0.0 mm | Extreme 57 |
| 22 Sept after | 28.5 °C | 9 % | 63 km/h | 0.0 mm | Extreme 64 |
| 23 Sept after | 25.8 °C | 12 % | 36 km/h | 0.0 mm | Very high 48 |
| 24 Sept after | 27.0 °C | 12 % | 31 km/h | 0.0 mm | Very high 46 |
| 25 Sept after | 29.7 °C | 7 % | 23 km/h | 0.0 mm | Very high 42 |
| 26 Sept after | 30.4 °C | 9 % | 36 km/h | 0.0 mm | Extreme 52 |
| 27 Sept after | 31.7 °C | 11 % | 37 km/h | 0.0 mm | Very high 48 |
| 28 Sept after | 31.3 °C | 8 % | 49 km/h | 0.0 mm | Extreme 58 |
| 29 Sept after | 31.3 °C | 10 % | 41 km/h | 0.0 mm | Extreme 54 |
| 30 Sept after | 31.1 °C | 12 % | 64 km/h | 0.3 mm | Extreme 65 |
| 1 Oct after | 25.2 °C | 21 % | 58 km/h | 0.2 mm | Extreme 57 |
Before and after, from space
Drag the line to compare the same ground before the fire and after it.
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 · CopernicusOn 21 September 2023 the air beside the fire reached 24 µg/m³ of PM2.5, but no daily average passed the WHO guideline (15).
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 · 18Every satellite heat detection, one by one, with time, satellite, power and coordinates.
| Date and time | Satellite | FRP (MW) | Lat | Lon |
|---|
Other fires nearby
Frequently asked questions
- How long did the Border fire last?
- It burned between 21 September 2023 and 21 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 503 hectares (5.0 km²). Other tallies, such as daily incident reports, may give slightly different figures.
- Which counties burned?
- The fire entered 2 counties: Grand (316 ha, 0.0 %); Mesa (188 ha, 0.0 %).
- What was the weather like?
- During the fire the temperature reached 28.2 °C, humidity dropped to 10 % and gusts hit 54 km/h. The fire danger index (FWI) reached 57, 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
- NIFC · National Interagency Fire Center ↗
- InciWeb · Incident Information System ↗
- MTBS · Monitoring Trends in Burn Severity ↗
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
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.