How long did the Moosomin 112B fire last?

The official perimeter only gives the start date (3 May 2023). The end comes from the heat detections inside the perimeter: it burned until 8 May 2023 (6 days from 3 May 2023), 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 mapped by Canada’s CWFIS (Natural Resources Canada) is 3,725 hectares (37.2 km²). Other tallies, such as those of provincial agencies, may give slightly different figures.

Which census subdivisions burned?

The fire entered 4 census subdivisions: Moosomin 112B (2,627 ha, 37 %); Saulteaux 159 (563 ha, 14 %); Meota No. 468 (533 ha, 0.7 %); Round Hill No. 467 (14 ha, 0.0 %).

What was the weather like?

During the fire the temperature reached 25.2 °C, humidity dropped to 14 % and gusts hit 35 km/h. The fire danger index (FWI) reached 20, class Moderate.

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 · 2023-05-03 → 2023-05-08

Moosomin 112B fire, May 2023 Moosomin 112B, Saulteaux 159, Meota No. 468

Out · last detection 6 May 2023, 19:04 UTC

The fire started on 3 May 2023 in Moosomin 112B, Canada, and satellites saw it burning for 6 days. Canada’s CWFIS (Natural Resources Canada) mapped an official burnt perimeter of 3,725 hectares from satellite imagery, spread across 4 census subdivisions.

It is the 258th largest in Saskatchewan since 2016 (of 482 with a page). Number 315 in Canada in 2023, of 489.

Compare with…

Burnt area: 3,725ha; official perimeter (CWFIS)
Duration: ≈ 6days; 3 May 2023 – 8 May 2023
Census subdivisions hit: 4; municipalities
Started on: 3 May; 2023
Heat detections: 425; in a single hotspot: 217 MW
Danger at start: 20; Moderate · FWI index
Average daily power: 2.7GW; detected power per day, on average

HOTSPOTS BY DAY 3 May8 May

Play back 6 May 2023

How it evolved, day by day

3 May 4 May 5 May 6 May

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

The weather it burned in

25°high

35km/h · peak gust

14%lowest humidity

It had gone 7 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.

How big is it?

It burned the equivalent of 2.4% of the area of London (37 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

Moosomin 112B where it started

2,627 ha reached on 3 May

37 %
Saulteaux 159

563 ha reached on 4 May

14 %
Meota No. 468

533 ha reached on 3 May

0.7 %
Round Hill No. 467

14 ha reached on 6 May

0.0 %

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 area0.10 ha

Residents< 20

Inside the perimeter there were about 0.10 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)
3 May	25.2 °C	14 %	35 km/h	0.0 mm	Moderate 20
4 May	27.0 °C	13 %	42 km/h	0.0 mm	High 26
5 May	18.0 °C	23 %	54 km/h	0.0 mm	High 28
6 May	15.0 °C	29 %	52 km/h	0.1 mm	High 24
7 May	17.8 °C	26 %	58 km/h	0.0 mm	High 28
8 May	17.5 °C	30 %	46 km/h	0.3 mm	High 22
9 May after	17.6 °C	37 %	27 km/h	0.2 mm	Moderate 15
10 May after	19.4 °C	32 %	18 km/h	0.3 mm	Moderate 15
11 May after	21.4 °C	27 %	19 km/h	0.0 mm	Moderate 15
12 May after	23.6 °C	24 %	23 km/h	0.5 mm	Moderate 19
13 May after	24.9 °C	21 %	28 km/h	0.0 mm	High 22

Before and after, from space

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

↔

Before · 26 Apr 2023

After · 15 May 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 5 May 2023 the air beside the fire reached 40 µg/m³ of PM2.5, but no daily average passed the WHO guideline (15).

PM2.5 peak40 µg/m³

Days over the guideline0 days

PM1058 µg/m³

Optical depth0.68

WHO 15

123456

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 · 425Every 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

Frequently asked questions

How long did the Moosomin 112B fire last?: The official perimeter only gives the start date (3 May 2023). The end comes from the heat detections inside the perimeter: it burned until 8 May 2023 (6 days from 3 May 2023), 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 mapped by Canada’s CWFIS (Natural Resources Canada) is 3,725 hectares (37.2 km²). Other tallies, such as those of provincial agencies, may give slightly different figures.
Which census subdivisions burned?: The fire entered 4 census subdivisions: Moosomin 112B (2,627 ha, 37 %); Saulteaux 159 (563 ha, 14 %); Meota No. 468 (533 ha, 0.7 %); Round Hill No. 467 (14 ha, 0.0 %).
What was the weather like?: During the fire the temperature reached 25.2 °C, humidity dropped to 14 % and gusts hit 35 km/h. The fire danger index (FWI) reached 20, class Moderate.
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 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

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What really happened?

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How we know this

Perimeter: NBAC (Natural Resources Canada), 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. 425 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