How long did the Poso Fire last?

The official perimeter only gives the start date (29 May 2021). The end comes from the heat detections inside the perimeter: it burned until 17 June 2021 (20 days from 29 May 2021), 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 777 hectares (7.8 km²). Other tallies, such as daily incident reports, may give slightly different figures.

Which counties burned?

The fire only entered Rio Arriba (774 ha, 0.0 %).

What was the weather like?

During the fire the temperature reached 30.5 °C, humidity dropped to 7 % and gusts hit 53 km/h. The fire danger index (FWI) reached 38, 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.

US · United States · 2021-05-29 → 2021-06-17

Poso Fire, May 2021 Rio Arriba

Out · last detection 17 Jun 2021, 09:17 UTC

The fire started on 29 May 2021 in Rio Arriba, United States, and satellites saw it burning for 20 days. United States agencies (MTBS / NIFC) mapped an official burnt perimeter of 777 hectares, spread across a single county.

It is the 145th largest in New Mexico since 2016 (of 204 with a page). Number 266 in United States in 2021, of 385.

Compare with…

Suggestions: Midnight · 2022 Francisquito · 2019 Gurule · 2019 Bonita · 2017

Burnt area: 777ha; official perimeter (MTBS / NIFC)
Duration: ≈ 20days; 29 May 2021 – 17 Jun 2021
Counties hit: 1; counties
Started on: 29 May; 2021
Heat detections: 147; in a single hotspot: 57 MW
Danger at start: 24; High · FWI index
Average daily power: 148MW; detected power per day, on average

HOTSPOTS BY DAY 29 May17 Jun

Play back 17 Jun 2021

How it evolved, day by day

8 Jun 12 Jun 14 Jun 16 Jun

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

53km/h · peak gust

7%lowest humidity

It had gone 5 days without rain (1 mm or more) when it started. Rain came after the fire: 2.2 mm on 18 Jun.

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 0.5% of the area of London (7.8 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

Rio Arriba where it started

774 ha reached on 8 Jun

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 2020

Built-up area< 0.1 ha

Residents< 20

Inside the perimeter there was no noticeable built-up land and almost nobody lived there (GHSL 2020, 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)
29 May	21.9 °C	19 %	40 km/h	0.2 mm	High 24
30 May	20.5 °C	24 %	45 km/h	2.2 mm	Low 8
31 May	15.1 °C	57 %	30 km/h	7.6 mm	Very low 0
1 Jun	18.1 °C	24 %	33 km/h	0.7 mm	Very low 2
2 Jun	19.5 °C	26 %	36 km/h	3.3 mm	Very low 2
3 Jun	21.5 °C	28 %	35 km/h	1.6 mm	Very low 3
4 Jun	22.8 °C	24 %	29 km/h	0.6 mm	Low 8
5 Jun	24.4 °C	23 %	47 km/h	1.1 mm	Low 10
6 Jun	24.4 °C	24 %	44 km/h	0.2 mm	Moderate 18
7 Jun	24.3 °C	14 %	36 km/h	0.0 mm	High 22
8 Jun	24.9 °C	11 %	46 km/h	0.0 mm	High 29
9 Jun	26.5 °C	10 %	28 km/h	0.0 mm	High 26
10 Jun	26.6 °C	7 %	53 km/h	0.0 mm	High 37
11 Jun	27.0 °C	7 %	37 km/h	0.0 mm	High 32
12 Jun	27.7 °C	9 %	42 km/h	0.0 mm	Very high 38
13 Jun	29.6 °C	10 %	40 km/h	0.0 mm	High 36
14 Jun	30.5 °C	7 %	30 km/h	0.0 mm	High 37
15 Jun	29.8 °C	15 %	32 km/h	0.9 mm	High 29
16 Jun	29.5 °C	12 %	46 km/h	0.0 mm	High 32
17 Jun	29.2 °C	15 %	28 km/h	0.4 mm	High 32
18 Jun after	27.8 °C	17 %	31 km/h	2.2 mm	High 23

Before and after, from space

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

↔

Before · 22 May 2021

After · 24 Jun 2021

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 · 147Every 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 Poso Fire last?: The official perimeter only gives the start date (29 May 2021). The end comes from the heat detections inside the perimeter: it burned until 17 June 2021 (20 days from 29 May 2021), 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 777 hectares (7.8 km²). Other tallies, such as daily incident reports, may give slightly different figures.
Which counties burned?: The fire only entered Rio Arriba (774 ha, 0.0 %).
What was the weather like?: During the fire the temperature reached 30.5 °C, humidity dropped to 7 % and gusts hit 53 km/h. The fire danger index (FWI) reached 38, 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

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. 147 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 2020, 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