How long did the Hatch Grade Fire last?

The official perimeter only gives the start date (29 September 2026). The end comes from the heat detections inside the perimeter: it burned until 30 September 2026 (2 days from 29 September 2026), 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 3,853 hectares (38.5 km²). Other tallies, such as daily incident reports, may give slightly different figures.

Which counties burned?

The fire entered 2 counties: Walla Walla (2,495 ha, 0.7 %); Umatilla (1,354 ha, 0.2 %).

Is the Hatch Grade Fire still active?

No fire detections since 30 Sept 2026, 20:49 UTC. A lack of detections is not an official extinction.

What was the weather like?

During the fire the temperature reached 25.9 °C, humidity dropped to 34 % and gusts hit 50 km/h. The fire danger index (FWI) reached 36, 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.

US · United States · 2026-09-29 → 2026-09-30

Hatch Grade Fire, September 2026 Walla Walla, Umatilla

Out · last detection 30 Sept 2026, 20:49 UTC

The fire started on 29 September 2026 in Walla Walla, United States, and satellites saw it burning for 2 days. United States agencies (MTBS / NIFC) mapped an official burnt perimeter of 3,853 hectares, spread across 2 counties.

It is the 80th largest in Washington since 2016 (of 285 with a page). Number 114 in United States in 2026, of 423.

The power measured by the satellite is low (19.3 MW in the strongest hotspot), more typical of grass or stubble burning, or a slow surface fire, than of a large crown fire.

Compare with…

Suggestions: Vansycle Canyon · 2025 Lambdin · 2026 Twin Sisters · 2026 Juniper Canyon · 2025

Burnt area: 3,853ha; official perimeter (MTBS / NIFC)
Duration: ≈ 2days; 29 Sept 2026 – 30 Sept 2026
Counties hit: 2; counties
Started on: 29 Sept; 2026
Heat detections: 47; in a single hotspot: 19 MW
Danger at start: 36; High · FWI index
Average daily power: 217MW; detected power per day, on average

HOTSPOTS BY DAY 29 Sept30 Sept

How it evolved, day by day

30 Sept 2026 · 217 MW · 47

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

The weather it burned in

26°high

50km/h · peak gust

34%lowest humidity

It had gone 3 days without rain (1 mm or more) when it started.

This area had burned before

0% of the perimeter overlaps earlier fires recorded since 2016: 2 ha in 2025.

2 ha Vansycle Canyon fire, June 2025 820 ha in total; the hectares shown are those it shares with this fire

How big is it?

It burned the equivalent of 2.4% of the area of London (39 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

Walla Walla where it started

2,495 ha reached on 30 Sept

0.7 %
Umatilla

1,354 ha reached on 30 Sept

0.2 %

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 2025

Built-up area0.91 ha

Residents< 20

Inside the perimeter there were about 0.91 hectares of built-up land and almost nobody lived there (GHSL 2025, 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. The GHSL 2025 epoch is a projection made from 2020 and earlier data.

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 Sept	25.9 °C	34 %	50 km/h	0.0 mm	High 36
30 Sept	22.9 °C	45 %	28 km/h	0.1 mm	High 23
1 Oct after	24.5 °C	27 %	21 km/h	0.0 mm	High 23
2 Oct after	27.3 °C	27 %	21 km/h	0.0 mm	High 24
3 Oct after	27.8 °C	28 %	23 km/h	0.0 mm	High 25
4 Oct after	26.1 °C	33 %	19 km/h	0.0 mm	High 23
5 Oct after	28.8 °C	20 %	22 km/h	0.0 mm	High 29
6 Oct after	27.2 °C	25 %	17 km/h	0.0 mm	High 29
7 Oct after	26.2 °C	29 %	20 km/h	0.0 mm	High 28
8 Oct after	26.4 °C	23 %	16 km/h	0.0 mm	High 28
9 Oct after	22.8 °C	38 %	55 km/h	0.0 mm	Very high 39
10 Oct after	16.2 °C	30 %	32 km/h	0.0 mm	High 29

Before and after, from space

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

↔

Before · 22 Sept 2026

After · 7 Oct 2026

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.

The smoke

CAMS · Copernicus

On 1 October 2026 the air beside the fire reached 28 µg/m³ of PM2.5. That day averaged 16: 1.1 times the WHO daily guideline (15).

PM2.5 peak28 µg/m³

Days over the guideline1 day

PM1030 µg/m³

Optical depth0.17

WHO 15

272829301

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 · 47Every 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 Hatch Grade Fire last?: The official perimeter only gives the start date (29 September 2026). The end comes from the heat detections inside the perimeter: it burned until 30 September 2026 (2 days from 29 September 2026), 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 3,853 hectares (38.5 km²). Other tallies, such as daily incident reports, may give slightly different figures.
Which counties burned?: The fire entered 2 counties: Walla Walla (2,495 ha, 0.7 %); Umatilla (1,354 ha, 0.2 %).
Is the Hatch Grade Fire still active?: No fire detections since 30 Sept 2026, 20:49 UTC. A lack of detections is not an official extinction.
What was the weather like?: During the fire the temperature reached 25.9 °C, humidity dropped to 34 % and gusts hit 50 km/h. The fire danger index (FWI) reached 36, 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 · 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.

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.

Report an error

What do you think is wrong?

Dates or duration Place or towns Burned area Name It was not a wildfire Same fire as another page Something else

What really happened?

Your connection to the fire (optional) Email (optional)

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.

How we know this

Perimeter: NIFC WFIGS (United States), 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. 47 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 2025, 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