How long did the Clear Hills fire last?

According to the heat detections seen by satellite inside the perimeter, it burned from 21 July 2023 to 10 November 2023 (113 days). The perimeter dates it from 21 July 2023 to 8 November 2023.

How much area did it burn?

The official perimeter mapped by Canada’s CWFIS (Natural Resources Canada) is 12,427 hectares (124.3 km²). Other tallies, such as those of provincial agencies, may give slightly different figures.

Which census subdivisions burned?

The fire only entered Clear Hills (12,442 ha, 0.8 %).

What was the weather like?

During the fire the temperature reached 27.5 °C, humidity dropped to 9 % and gusts hit 58 km/h. The fire danger index (FWI) reached 30, class High.

Where does this data come from?

From the official burnt perimeter of Canada’s CWFIS (NBAC, Natural Resources Canada) or, for the current season and until NBAC publishes it, the one rebuilt by GWIS (Copernicus); from NASA FIRMS VIIRS hotspots; and from the administrative boundaries of Canada. It is not an official report.

CA · Canada · 2023-07-21 → 2023-11-10

Clear Hills fire, July 2023 Clear Hills

Out · last detection 9 Nov 2023, 10:47 UTC

The fire started on 21 July 2023 in Clear Hills, Canada, and satellites saw it burning for 113 days. Canada’s CWFIS (Natural Resources Canada) mapped an official burnt perimeter of 12,427 hectares from satellite imagery, spread across a single census subdivision.

It is the 60th largest in Alberta since 2016 (of 243 with a page). Number 141 in Canada in 2023, of 489.

Compare with…

Suggestions: Clear Hills · 2023 Clear Hills · 2016

Burnt area: 12,427ha; official perimeter (CWFIS)
Duration: 113days; 21 Jul 2023 – 10 Nov 2023
Census subdivisions hit: 1; municipalities
Started on: 21 Jul; 2023
Heat detections: 2,571; in a single hotspot: 275 MW
Danger at start: 7; Low · FWI index
Average daily power: 718MW; detected power per day, on average

HOTSPOTS BY DAY 21 Jul10 Nov

Play back 9 Nov 2023

How it evolved, day by day

22 Jul 28 Aug 2 Sept 3 Sept 10 Sept 17 Sept 23 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

28°high

58km/h · peak gust

9%lowest humidity

It had gone 2 days without rain (1 mm or more) when it started. Rain came after the fire: 1.8 mm on 12 Nov.

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 7.8% of the area of London (124 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 census subdivision

Clear Hills where it started

12,442 ha reached on 22 Jul

0.8 %

Burnt area inside each census subdivision, 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 area< 0.1 ha

Residents< 20

Inside the perimeter there was no noticeable 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)
21 Jul	26.0 °C	38 %	21 km/h	0.4 mm	Low 7
22 Jul	23.4 °C	46 %	33 km/h	4.0 mm	Very low 1
23 Jul	21.6 °C	30 %	29 km/h	0.5 mm	Very low 5
24 Jul	17.4 °C	53 %	29 km/h	16.6 mm	Very low 0
25 Jul	14.9 °C	77 %	36 km/h	15.4 mm	Very low 0
26 Jul	17.3 °C	77 %	34 km/h	13.8 mm	Very low 0
27 Jul	17.9 °C	44 %	37 km/h	0.0 mm	Very low 0
28 Jul	19.6 °C	38 %	32 km/h	0.0 mm	Very low 1
29 Jul	21.9 °C	33 %	34 km/h	0.0 mm	Very low 5
30 Jul	23.4 °C	38 %	22 km/h	0.6 mm	Low 6
31 Jul	14.9 °C	76 %	28 km/h	11.2 mm	Very low 0
1 Aug	16.6 °C	70 %	24 km/h	7.6 mm	Very low 0
2 Aug	19.6 °C	49 %	18 km/h	4.9 mm	Very low 0
3 Aug	17.9 °C	66 %	28 km/h	11.1 mm	Very low 0
4 Aug	20.6 °C	44 %	32 km/h	1.2 mm	Very low 0
5 Aug	23.7 °C	37 %	22 km/h	0.0 mm	Very low 1
6 Aug	25.4 °C	36 %	20 km/h	2.0 mm	Very low 1
7 Aug	22.6 °C	57 %	31 km/h	4.8 mm	Very low 0
8 Aug	14.9 °C	91 %	27 km/h	8.2 mm	Very low 0
9 Aug	18.5 °C	71 %	23 km/h	4.9 mm	Very low 0
10 Aug	15.5 °C	74 %	45 km/h	12.5 mm	Very low 0
11 Aug	18.9 °C	49 %	34 km/h	0.4 mm	Very low 0
12 Aug	21.3 °C	35 %	37 km/h	0.0 mm	Very low 1
13 Aug	25.9 °C	35 %	56 km/h	0.0 mm	Low 8
14 Aug	21.3 °C	30 %	38 km/h	0.1 mm	Low 8
15 Aug	20.1 °C	50 %	55 km/h	5.2 mm	Very low 1
16 Aug	23.2 °C	35 %	41 km/h	0.0 mm	Very low 4
17 Aug	19.9 °C	40 %	33 km/h	1.8 mm	Very low 2
18 Aug	10.9 °C	54 %	42 km/h	1.6 mm	Very low 1
19 Aug	19.0 °C	40 %	30 km/h	0.1 mm	Very low 3
20 Aug	21.7 °C	32 %	28 km/h	0.0 mm	Low 7
21 Aug	20.7 °C	34 %	32 km/h	0.0 mm	Low 9
22 Aug	19.6 °C	53 %	27 km/h	1.0 mm	Very low 4
23 Aug	16.3 °C	70 %	38 km/h	1.1 mm	Very low 2
24 Aug	19.9 °C	46 %	19 km/h	0.0 mm	Very low 5
25 Aug	23.3 °C	37 %	32 km/h	0.0 mm	Low 9
26 Aug	25.5 °C	35 %	33 km/h	0.0 mm	Moderate 12
27 Aug	25.6 °C	38 %	31 km/h	0.0 mm	Moderate 13
28 Aug	27.5 °C	33 %	27 km/h	0.0 mm	Moderate 14
29 Aug	25.6 °C	33 %	26 km/h	0.0 mm	Moderate 14
30 Aug	22.7 °C	49 %	21 km/h	8.0 mm	Very low 1
31 Aug	20.0 °C	43 %	38 km/h	0.0 mm	Very low 3
1 Sept	24.4 °C	28 %	56 km/h	0.0 mm	Moderate 14
2 Sept	19.0 °C	27 %	41 km/h	0.0 mm	Moderate 15
3 Sept	11.6 °C	51 %	41 km/h	0.6 mm	Low 11
4 Sept	14.1 °C	36 %	27 km/h	0.0 mm	Low 10
5 Sept	11.6 °C	61 %	33 km/h	4.6 mm	Very low 0
6 Sept	14.0 °C	43 %	35 km/h	0.0 mm	Very low 2
7 Sept	16.6 °C	36 %	39 km/h	0.0 mm	Low 6
8 Sept	17.7 °C	32 %	22 km/h	0.0 mm	Low 8
9 Sept	19.3 °C	31 %	27 km/h	0.0 mm	Low 11
10 Sept	22.3 °C	31 %	34 km/h	0.0 mm	Moderate 14
11 Sept	19.5 °C	36 %	46 km/h	0.0 mm	Moderate 16
12 Sept	18.8 °C	42 %	41 km/h	0.2 mm	Moderate 14
13 Sept	13.8 °C	44 %	58 km/h	1.3 mm	Low 8
14 Sept	17.3 °C	29 %	31 km/h	0.0 mm	Low 10
15 Sept	23.3 °C	9 %	55 km/h	0.0 mm	High 30
16 Sept	17.5 °C	27 %	40 km/h	0.0 mm	High 21
17 Sept	17.6 °C	34 %	56 km/h	0.0 mm	High 24
18 Sept	12.9 °C	39 %	53 km/h	0.0 mm	Moderate 20
19 Sept	11.8 °C	42 %	36 km/h	0.0 mm	Moderate 15
20 Sept	14.4 °C	36 %	23 km/h	0.0 mm	Moderate 14
21 Sept	18.1 °C	40 %	43 km/h	0.0 mm	Moderate 17
22 Sept	22.2 °C	31 %	37 km/h	0.0 mm	Moderate 18
23 Sept	17.5 °C	34 %	26 km/h	1.4 mm	Low 8
24 Sept	10.0 °C	64 %	45 km/h	3.1 mm	Very low 1
25 Sept	10.4 °C	67 %	45 km/h	4.5 mm	Very low 0
26 Sept	14.2 °C	50 %	38 km/h	0.6 mm	Very low 2
27 Sept	12.1 °C	57 %	36 km/h	0.9 mm	Very low 3
28 Sept	7.7 °C	88 %	24 km/h	8.0 mm	Very low 0
29 Sept	6.8 °C	80 %	16 km/h	2.3 mm	Very low 0
30 Sept	9.3 °C	65 %	30 km/h	1.1 mm	Very low 0
1 Oct	11.3 °C	52 %	40 km/h	0.0 mm	Very low 1
2 Oct	12.0 °C	50 %	35 km/h	0.3 mm	Very low 1
3 Oct	11.6 °C	47 %	47 km/h	0.0 mm	Very low 5
4 Oct	7.4 °C	30 %	58 km/h	0.4 mm	Low 8
5 Oct	4.5 °C	37 %	30 km/h	0.0 mm	Low 6
6 Oct	15.4 °C	45 %	54 km/h	0.0 mm	Low 9
7 Oct	20.4 °C	32 %	27 km/h	0.0 mm	Low 10
8 Oct	20.1 °C	29 %	32 km/h	0.0 mm	Moderate 12
9 Oct	18.4 °C	37 %	28 km/h	0.0 mm	Moderate 12
10 Oct	14.7 °C	51 %	19 km/h	0.5 mm	Low 10
11 Oct	11.4 °C	71 %	22 km/h	7.4 mm	Very low 0
12 Oct	12.9 °C	58 %	24 km/h	0.2 mm	Very low 0
13 Oct	8.9 °C	72 %	42 km/h	0.0 mm	Very low 1
14 Oct	8.8 °C	71 %	31 km/h	0.0 mm	Very low 1
15 Oct	11.8 °C	56 %	31 km/h	0.0 mm	Very low 2
16 Oct	11.2 °C	53 %	28 km/h	1.5 mm	Very low 1
17 Oct	9.1 °C	71 %	30 km/h	3.0 mm	Very low 0
18 Oct	12.9 °C	52 %	53 km/h	1.3 mm	Very low 1
19 Oct	11.2 °C	49 %	49 km/h	0.3 mm	Very low 3
20 Oct	10.4 °C	40 %	42 km/h	0.0 mm	Very low 5
21 Oct	-0.3 °C	75 %	33 km/h	0.0 mm	Very low 3
22 Oct	-4.7 °C	60 %	34 km/h	4.1 mm	Very low 0
23 Oct	-7.2 °C	49 %	24 km/h	0.0 mm	Very low 0
24 Oct	-5.9 °C	46 %	31 km/h	0.0 mm	Very low 1
25 Oct	-6.6 °C	50 %	34 km/h	0.0 mm	Very low 1
26 Oct	-2.5 °C	57 %	38 km/h	0.3 mm	Very low 1
27 Oct	-1.7 °C	43 %	27 km/h	0.0 mm	Very low 1
28 Oct	0.6 °C	50 %	38 km/h	0.0 mm	Very low 2
29 Oct	-0.5 °C	58 %	22 km/h	0.0 mm	Very low 2
30 Oct	1.0 °C	58 %	19 km/h	0.0 mm	Very low 2
31 Oct	3.5 °C	55 %	23 km/h	0.1 mm	Very low 2
1 Nov	2.3 °C	72 %	18 km/h	1.3 mm	Very low 1
2 Nov	0.0 °C	73 %	26 km/h	0.0 mm	Very low 1
3 Nov	-0.2 °C	78 %	24 km/h	0.0 mm	Very low 1
4 Nov	-2.3 °C	85 %	39 km/h	3.3 mm	Very low 0
5 Nov	-1.9 °C	93 %	28 km/h	6.1 mm	Very low 0
6 Nov	0.0 °C	90 %	15 km/h	0.0 mm	Very low 0
7 Nov	0.1 °C	78 %	51 km/h	2.0 mm	Very low 0
8 Nov	-0.3 °C	67 %	35 km/h	0.0 mm	Very low 0
9 Nov	-1.8 °C	82 %	31 km/h	0.0 mm	Very low 0
10 Nov	2.3 °C	61 %	38 km/h	0.0 mm	Very low 0
11 Nov after	2.3 °C	66 %	33 km/h	0.7 mm	Very low 0
12 Nov after	-0.4 °C	72 %	24 km/h	1.8 mm	Very low 0

Before and after, from space

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

↔

Before · 14 Jul 2023

After · 17 Nov 2023

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 25 September 2023 the air beside the fire reached 361 µg/m³ of PM2.5. That day averaged 195: 13 times the WHO daily guideline (15).

PM2.5 peak361 µg/m³

Days over the guideline42 days

PM10516 µg/m³

Optical depth7.17

WHO 15

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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 · 2,571Every 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 Canada ›

Frequently asked questions

How long did the Clear Hills fire last?: According to the heat detections seen by satellite inside the perimeter, it burned from 21 July 2023 to 10 November 2023 (113 days). The perimeter dates it from 21 July 2023 to 8 November 2023.
How much area did it burn?: The official perimeter mapped by Canada’s CWFIS (Natural Resources Canada) is 12,427 hectares (124.3 km²). Other tallies, such as those of provincial agencies, may give slightly different figures.
Which census subdivisions burned?: The fire only entered Clear Hills (12,442 ha, 0.8 %).
What was the weather like?: During the fire the temperature reached 27.5 °C, humidity dropped to 9 % and gusts hit 58 km/h. The fire danger index (FWI) reached 30, class High.
Where does this data come from?: From the official burnt perimeter of Canada’s CWFIS (NBAC, Natural Resources Canada) or, for the current season and until NBAC publishes it, the one rebuilt by GWIS (Copernicus); from NASA FIRMS VIIRS hotspots; and from the administrative boundaries of Canada. 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 ↗
CWFIS · Interactive map ↗

History of this page · 1 Changes in area, dates, name, official record or merged pages, compared every night since 24 October 2026.

25 October 2026 Last day with fire: 8 November 2023 → 10 November 2023.

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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What really happened?

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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.

How we know this

Perimeter: NBAC (Natural Resources Canada), official.
Dates adjusted with the VIIRS detections inside the perimeter, which said 21 July 2023 to 8 November 2023. 2,571 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: it comes from the National Burned Area Composite (NBAC) of the Canadian Wildland Fire Information System (CWFIS), Natural Resources Canada, which maps it on satellite imagery and publishes it under the Open Government Licence – Canada. Until NBAC publishes the current season, this year’s fires carry the perimeter rebuilt from heat detections by GWIS (Copernicus, CC BY 4.0), which is approximate. Heat detections come from the VIIRS sensors aboard Suomi-NPP and NOAA-20, distributed by NASA FIRMS at 375 m resolution. Census subdivision boundaries come from geoBoundaries ADM3 (Open Data Commons Open Database License 1.0). The area per census subdivision is computed by WorldFires by crossing the perimeter with those boundaries, so it may differ slightly from official figures.

Where it burned